Bump actions/upload-artifact from 5 to 6

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]>

Author: dependabot[bot]

.github/workflows/fetch_versions.yml

@@ -55,7 +55,7 @@ jobs:
         run: |
           go run ./internal/cmd/fetcher .
       - name: Archive plugin generated code
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: plugin-generated-code
           path: |

.github/workflows/pr.yml

@@ -77,7 +77,7 @@ jobs:
     - name: Test
       run: make test
     - name: Archive plugin generated code
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       if: ${{ failure() }}
       with:
         name: plugin-generated-code