.github/workflows: enable GitHub artifact attestations

Author: 0x2b3bfa0

.github/workflows/build.yml

@@ -5,7 +5,9 @@ on:
   push:
   pull_request:
 permissions:
+  attestations: write
   contents: read
+  id-token: write
 jobs:
   build:
     name: Build binaries
@@ -61,6 +63,10 @@ jobs:
           GOOS: ${{ matrix.GOOS }}
           GOARCH: ${{ matrix.GOARCH }}
           GOARM: ${{ matrix.GOARM }}
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@v2
+        with:
+          subject-path: age-*
       - name: Upload workflow artifacts
         uses: actions/upload-artifact@v4
         with: