Merge pull request #1078 from sigstore/renovate/sigstore-sigstore-conformance-0.x

chore(deps): update sigstore/sigstore-conformance action to v0.0.21

Author: loosebazooka

.github/workflows/conformance.yml

@@ -54,7 +54,7 @@ jobs:
           java-version: ${{ matrix.java-version }}
           distribution: 'temurin'
 
-      - uses: sigstore/sigstore-conformance@1d8b0cdd88fa7fb5a8510e51faf6ccad8c96f10a # v0.0.20
+      - uses: sigstore/sigstore-conformance@244638a7a138ae9f6106cfe2d44a698eccd3bef7 # v0.0.21
         with:
           entrypoint: ${{ github.workspace }}/sigstore-cli/sigstore-cli-server
           environment: ${{ matrix.sigstore-env }}