Bump golang to 1.13 in Dockerfiles

Signed-off-by: Silvin Lubecki <silvin.lubecki@docker.com>

Dockerfile

@@ -8,7 +8,7 @@ FROM docker:$DOCKERD_VERSION AS dockerd-release
 # xgo is a helper for golang cross-compilation
 FROM --platform=$BUILDPLATFORM tonistiigi/xx:golang@sha256:6f7d999551dd471b58f70716754290495690efa8421e0a1fcf18eb11d0c0a537 AS xgo
 
-FROM --platform=$BUILDPLATFORM golang:1.12-alpine AS gobase
+FROM --platform=$BUILDPLATFORM golang:1.13-alpine AS gobase
 COPY --from=xgo / /
 RUN apk add --no-cache file git
 ENV GOFLAGS=-mod=vendor

hack/dockerfiles/lint.Dockerfile

@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1.0-experimental
 
-FROM golang:1.12-alpine
+FROM golang:1.13-alpine
 RUN  apk add --no-cache git
 RUN  go get -u gopkg.in/alecthomas/gometalinter.v1 \
   && mv /go/bin/gometalinter.v1 /go/bin/gometalinter \

hack/dockerfiles/vendor.Dockerfile

@@ -1,5 +1,5 @@
 # syntax = docker/dockerfile:1.0-experimental
-FROM golang:1.12-alpine AS vendored
+FROM golang:1.13-alpine AS vendored
 RUN  apk add --no-cache git rsync
 WORKDIR /src
 RUN --mount=target=/context \