chore(deps): update actions/cache action to v5 (#1333)

* chore(deps): update actions/cache action to v5

Generated by renovateBot

* generated protobuf

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Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/buildtest.yaml

@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
-      - uses: actions/cache@v4
+      - uses: actions/cache@v5
         with:
           path: |
             ~/go/pkg/mod