build(deps): bump actions/upload-artifact from 5 to 6 (#6177)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

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

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

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -254,7 +254,7 @@ jobs:
         run: ${{ matrix.extra }} dev/ci.sh ${{ matrix.test-suites }}
       - name: "Upload pdf manuals"
         if: ${{ contains(matrix.test-suites, 'makemanuals') }}
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           if-no-files-found: error
           name: manuals-pdf
@@ -265,7 +265,7 @@ jobs:
             doc/tut/manual.pdf
       - name: "Upload html manuals"
         if: ${{ contains(matrix.test-suites, 'makemanuals') }}
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           if-no-files-found: error
           name: manuals-html

.github/workflows/release.yml

@@ -152,7 +152,7 @@ jobs:
       #
       # Warning: the result is a single .zip file (so things are compressed twice).
       - name: "Upload GAP tarball"
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           if-no-files-found: error
           name: gap
@@ -161,7 +161,7 @@ jobs:
 
       # Always upload metadata, and keep longer, since it is much smaller.
       - name: "Upload JSON metadata"
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           if-no-files-found: error
           name: "JSON metadata"
@@ -239,7 +239,7 @@ jobs:
       # Artifacts live for 1 day, i.e. until the next cron job runs.
       - name: "Upload the installer as an artifact"
         if: ${{ github.event_name == 'schedule' }}
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           if-no-files-found: error
           name: gap-${{ env.GAP_VERSION }}-x86_64.exe