Migrate to actions/attest (#2952)

Migrate from now-deprecated attestation action to `actions/attest`.

Author: martincostello

.github/workflows/build.yml

@@ -402,7 +402,7 @@ jobs:
         }
 
     - name: Attest artifacts
-      uses: actions/attest-build-provenance@96278af6caaf10aea03fd8d33a09a777ca52d62f # v3.2.0
+      uses: actions/attest@59d89421af93a897026c735860bf21b6eb4f7b26 # v4.1.0
       with:
         subject-path: |
           ./artifacts/polly.spdx.json

.github/workflows/dependabot-approve.yml

@@ -39,7 +39,7 @@ jobs:
       - name: Approve pull request and enable auto-merge
         shell: bash
         if: |
-          contains(steps.dependabot-metadata.outputs.dependency-names, 'actions/attest-build-provenance') ||
+          contains(steps.dependabot-metadata.outputs.dependency-names, 'actions/attest') ||
           contains(steps.dependabot-metadata.outputs.dependency-names, 'actions/cache') ||
           contains(steps.dependabot-metadata.outputs.dependency-names, 'actions/checkout') ||
           contains(steps.dependabot-metadata.outputs.dependency-names, 'actions/create-github-app-token') ||