fix(ci): artifact@v3 -> artifact@v4

[wdconinc]

Briefly, what does this PR introduce?

Upgrade {upload,download}-artifact@v3 to v4. https://github.com/actions/upload-artifact/blob/main/docs/MIGRATION.md

[Copilot]

Pull request overview

This PR upgrades GitHub Actions artifact actions from v3 to v4 across the CI workflow. However, the upgrade introduces critical breaking changes that have not been addressed.

Changes:

• Updated all 9 instances of actions/upload-artifact from v3 to v4
• Updated all 10 instances of actions/download-artifact from v3 to v4

Comments suppressed due to low confidence (4)

.github/workflows/ci.yml:390

• The postprocess job has a matrix with 55 parallel runs that all upload to the same artifact name "postprocess". In upload-artifact@v4, artifacts with the same name will overwrite each other instead of merging like in v3. You need to make artifact names unique per matrix job by including matrix variables in the name, for example: "postprocess_${{matrix.mode}}${{matrix.pname}}${{matrix.recon}}"

      - uses: actions/upload-artifact@v4
        with:
          name: postprocess
          retention-days: 30
          path: |
            out/*.images/*.png
            out/*.root

.github/workflows/ci.yml:467

• The comparison job has a matrix with 14 parallel runs that all upload to the same artifact name "comparison". In upload-artifact@v4, artifacts with the same name will overwrite each other instead of merging like in v3. You need to make artifact names unique per matrix job by including matrix variables in the name, for example: "comparison_${{matrix.pname}}_${{matrix.recon}}"

      - uses: actions/upload-artifact@v4
        with:
          name: comparison
          retention-days: 30
          path: |
            out/comparison*.images/*.png
            out/comparison*.root

.github/workflows/ci.yml:294

• The analysis_fullsim job has a matrix with 68 parallel runs that all upload to the same artifact name "analysis". In upload-artifact@v4, artifacts with the same name will overwrite each other instead of merging like in v3. You need to make artifact names unique per matrix job by including matrix variables in the name, for example: "analysis_fullsim_${{matrix.detector}}${{matrix.aname}}${{matrix.recon}}"

      - uses: actions/upload-artifact@v4
        with:
          name: analysis
          retention-days: 7
          path: out

.github/workflows/ci.yml:227

• The analysis_fastsim job has a matrix with 8 parallel runs that all upload to the same artifact name "analysis". In upload-artifact@v4, artifacts with the same name will overwrite each other instead of merging like in v3. You need to make artifact names unique per matrix job by including matrix variables in the name, for example: "analysis_fastsim_${{matrix.aname}}_${{matrix.recon}}"

      - uses: actions/upload-artifact@v4
        with:
          name: analysis
          retention-days: 7
          path: out

---

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[Copilot]

This download step expects to download the "analysis" artifact, but since the analysis_fastsim and analysis_fullsim jobs will need to upload with unique artifact names per matrix job (due to v4 requirements), this download step will also need to be updated to download all the individual artifacts using a pattern or merge approach. Consider using actions/download-artifact@v4 with the merge-multiple option or downloading each artifact individually.

Suggested change

	name: analysis
	pattern: analysis*
	merge-multiple: true

[Copilot]

This download step expects to download the "analysis" artifact, but since the analysis_fastsim and analysis_fullsim jobs will need to upload with unique artifact names per matrix job (due to v4 requirements), this download step will also need to be updated to download all the individual artifacts using a pattern or merge approach. Consider using actions/download-artifact@v4 with the merge-multiple option or downloading each artifact individually.

Suggested change

	name: analysis
	pattern: analysis-*
	merge-multiple: true

[Copilot]

This download step expects to download the "comparison" artifact, but since the comparison job will need to upload with unique artifact names per matrix job (due to v4 requirements), this download step will also need to be updated to download all the individual artifacts using a pattern or merge approach. Consider using actions/download-artifact@v4 with the merge-multiple option or downloading each artifact individually.

Suggested change

	name: comparison
	pattern: comparison-*
	merge-multiple: true

[Copilot]

This download step expects to download the "postprocess" artifact, but since the postprocess job will need to upload with unique artifact names per matrix job (due to v4 requirements), this download step will also need to be updated to download all the individual artifacts using a pattern or merge approach. Consider using actions/download-artifact@v4 with the merge-multiple option or downloading each artifact individually.

[Copilot]

The delphes_fastsim job has a matrix with 4 parallel runs that all upload to the same artifact name "x_fastsim_delphes". In upload-artifact@v4, artifacts with the same name will overwrite each other instead of merging like in v3. You need to make artifact names unique per matrix job by including the matrix variable in the name, for example: "x_fastsim_delphes_${{matrix.id}}"

Suggested change

	name: x_fastsim_delphes
	name: x_fastsim_delphes_${{matrix.id}}