Bump actions/checkout from 5 to 6 (#253)

* Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

* Restrict jupyter book version

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Michael Howard <[email protected]>

Author: dependabot[bot]

.github/workflows/deploy-preview.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout book
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python 3.12
         if: github.event.action != 'closed'

.github/workflows/deploy.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Checkout book
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python 3.12
         uses: actions/setup-python@v6

requirements.txt

@@ -1 +1 @@
-jupyter-book
+jupyter-book<2