Update alpine:3.21 Docker digest to a8560b3

Signed-off-by: red-hat-konflux <126015336+red-hat-konflux[bot]@users.noreply.github.com>

Author: red-hat-konflux[bot]

internal/witness/cmd/feeder/Dockerfile

@@ -18,7 +18,7 @@ COPY . .
 RUN go build -o /build/bin/feeder ./internal/witness/cmd/feeder
 
 # Build release image
-FROM alpine:3.21@sha256:21dc6063fd678b478f57c0e13f47560d0ea4eeba26dfc947b2a4f81f686b9f45
+FROM alpine:3.21@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c
 
 COPY --from=builder /build/bin/feeder /bin/feeder
 ENTRYPOINT ["/bin/feeder"]