update gcloud to 437.0.1 (#24)

This version is latest at time of commit.

Dockerfile

@@ -11,7 +11,7 @@ RUN BUILD_DATE=$(date +%F-%T) && CGO_ENABLED=0 GOOS=linux go build -o drone-clou
     -ldflags "-s -w -extldflags \"-static\" -X main.BuildHash=$SHA1 -X main.BuildTag=$TAG -X main.BuildDate=$BUILD_DATE" .
 RUN ./drone-cloud-run -v
 
-FROM       gcr.io/google.com/cloudsdktool/cloud-sdk:405.0.0-alpine as release
+FROM       gcr.io/google.com/cloudsdktool/cloud-sdk:437.0.1-alpine as release
 RUN        apk --no-cache add ca-certificates
 RUN        gcloud components install alpha beta
 COPY       --from=builder /go/src/github.com/oliver006/drone-cloud-run/drone-cloud-run /bin/drone-cloud-run