Update actions/attest-build-provenance action to v4 (#145)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Anuraag (Rag) Agrawal <anuraaga@gmail.com>

Author: renovate[bot]

.github/workflows/release.yaml

@@ -42,7 +42,7 @@ jobs:
           uv run python scripts/generate_wheels.py
         working-directory: protoc-gen-connect-python
 
-      - uses: actions/attest-build-provenance@96278af6caaf10aea03fd8d33a09a777ca52d62f # v3.2.0
+      - uses: actions/attest-build-provenance@a2bbfa25375fe432b6a289bc6b6cd05ecd0c4c32 # v4.1.0
         with:
           subject-checksums: out/checksums.txt