fix(ci): Update extension-validation workflow granting expected token permissions

See https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#jobsjob_idpermissions

Author: jcfr

.github/workflows/extension-validation.yml

@@ -14,6 +14,9 @@ concurrency:
 jobs:
   validate-extensions:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2