deps: Update alpine:3 Docker digest to 51183f2

Author: renovate-bot

Dockerfile.alpine

@@ -26,7 +26,7 @@ RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
     go build -ldflags "-X github.com/GoogleCloudPlatform/cloud-sql-proxy/v2/cmd.metadataString=container.alpine"
 
 # Final stage
-FROM alpine:3@sha256:a107a3c031732299dd9dd607bb13787834db2de38cfa13f1993b7105e4814c60
+FROM alpine:3@sha256:51183f2cfa6320055da30872f211093f9ff1d3cf06f39a0bdb212314c5dc7375
 
 LABEL org.opencontainers.image.source="https://github.com/GoogleCloudPlatform/cloud-sql-proxy"