Bump actions/setup-go from 5 to 6 (#36261)

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

---
updated-dependencies:
- dependency-name: actions/setup-go
  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/build_release_candidate.yml

@@ -449,7 +449,7 @@ jobs:
           then
             echo "Must provide an apache password to stage artifacts to https://dist.apache.org/repos/dist/dev/beam/"
           fi
-      - uses: actions/setup-go@v5
+      - uses: actions/setup-go@v6
         with:
           go-version: '1.24'
       - name: Import GPG key

.github/workflows/tour_of_beam_backend.yml

@@ -42,7 +42,7 @@ jobs:
         working-directory: ./learning/tour-of-beam/backend
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-go@v5
+      - uses: actions/setup-go@v6
         with:
           # pin to the biggest Go version supported by Cloud Functions runtime
           go-version: '1.16'