Update Golang 1.13.5

go1.13.5 (released 2019/12/04) includes fixes to the go command, the runtime, the
linker, and the net/http package. See the Go 1.13.5 milestone on our issue tracker
for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.13.5+label%3ACherryPickApproved

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

.appveyor.yml

@@ -13,7 +13,7 @@ environment:
   GOPATH: C:\gopath
   CGO_ENABLED: 1
   matrix:
-    - GO_VERSION: 1.13.4
+    - GO_VERSION: 1.13.5
 
 before_build:
   - choco install -y mingw --version 5.3.0

.travis.yml

@@ -10,7 +10,7 @@ os:
 - linux
 
 go:
-  - "1.13.4"
+  - "1.13.5"
 
 env:
   - TRAVIS_GOOS=linux TEST_RUNTIME=io.containerd.runc.v1 TRAVIS_CGO_ENABLED=1 TRAVIS_DISTRO=bionic GOPROXY=direct

contrib/Dockerfile.test

@@ -6,7 +6,7 @@
 # 3.) $ make binaries install test
 #
 
-ARG GOLANG_VERSION=1.13.4
+ARG GOLANG_VERSION=1.13.5
 
 FROM golang:${GOLANG_VERSION} AS golang-base
 RUN mkdir -p /go/src/github.com/containerd/containerd