Try GHA build fixes

Author: animetosho

.github/workflows/build-dev-mac-x64.yml

@@ -16,7 +16,7 @@ jobs:
         working-directory: nexe
       - uses: actions/setup-python@v5
         with:
-          python-version: '3.11'
+          python-version: '3.9'  # 'pipes' removed in Python 3.13, 'rU' mode unsupported in 3.11
       - run: node build
         working-directory: nexe
       - run: nexe/parpar --version

.github/workflows/build-dev-win64.yml

@@ -21,7 +21,7 @@ jobs:
         working-directory: nexe
       # diagnose weird execution failure
       - run: |
-          "C:\Program Files\Git\usr\bin\sed" -i "s/child_process_1\.spawn/this.log.step('Executing ' + command + ' ' + args); \0/" node_modules/nexe/lib/compiler.js
+          "C:\Program Files\Git\usr\bin\sed" "-i" "s/child_process_1\.spawn/this.log.step('Executing ' + command + ' ' + args); \0/" node_modules/nexe/lib/compiler.js
         working-directory: nexe
       - run: node build
         working-directory: nexe

.github/workflows/build.yml

@@ -227,7 +227,7 @@ jobs:
         working-directory: nexe
       - uses: actions/setup-python@v5
         with:
-          python-version: '3.11'
+          python-version: '3.9'  # 'pipes' removed in Python 3.13, 'rU' mode unsupported in 3.11
       - run: node build
         working-directory: nexe
       - run: nexe/parpar --version