ci: add provenance action to check for downgrades in provenance

Author: danielroe

.github/workflows/provenance.yml

@@ -0,0 +1,23 @@
+
+name: ci
+
+on:
+push:
+branches:
+ - main
+pull_request:
+branches:
+ - main
+permissions:
+contents: read
+jobs:
+check-provenance:
+runs-on: ubuntu-latest
+steps:
+ - uses: actions/checkout@v4
+with:
+fetch-depth: 0
+ - name: Check provenance downgrades
+uses: danielroe/provenance-action@a5a718233ca12eff67651fcf29a030bbbd5b3ca1 # v0.1.0
+with:
+fail-on-provenance-change: true