Update to Golang 1.12.13

go1.12.13 (released 2019/10/31) fixes an issue on macOS 10.15 Catalina
where the non-notarized installer and binaries were being rejected by
Gatekeeper. Only macOS users who hit this issue need to update.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.appveyor.yml

@@ -12,7 +12,7 @@ environment:
   GOPATH: C:\gopath
   CGO_ENABLED: 1
   matrix:
-    - GO_VERSION: 1.12.12
+    - GO_VERSION: 1.12.13
 
 before_build:
   - choco install -y mingw --version 5.3.0

.travis.yml

@@ -10,7 +10,7 @@ os:
 - linux
 
 go:
-  - "1.12.x"
+  - "1.12.13"
 
 env:
   - TRAVIS_GOOS=linux TEST_RUNTIME=io.containerd.runc.v1 TRAVIS_CGO_ENABLED=1 TRAVIS_DISTRO=bionic

contrib/Dockerfile.test

@@ -6,7 +6,7 @@
 # 3.) $ make binaries install test
 #
 
-ARG GOLANG_VERSION=1.12.12
+ARG GOLANG_VERSION=1.12.13
 
 FROM golang:${GOLANG_VERSION} AS golang-base
 RUN mkdir -p /go/src/github.com/containerd/containerd