Update golang to 1.15

Since RHEL-8.4 now have 1.15 in offical repo so better to use it
for all our CI which will consist with what we build downstream.

.circleci/config.yml

@@ -7,7 +7,7 @@ jobs:
     macos:
       xcode: "10.0.0"
     environment:
-      GOVERSION: "1.14.13"
+      GOVERSION: "1.15.13"
 
 ## Build crc
     steps:
@@ -44,7 +44,7 @@ jobs:
     machine:
       image: ubuntu-2004:202101-01
     environment:
-      GOVERSION: "1.14.13"
+      GOVERSION: "1.15.13"
       CONTAINER_RUNTIME: "docker"
     steps:
       - checkout

.travis.yml

@@ -1,7 +1,7 @@
 dist: bionic
 language: go
 go:
-  - 1.14.13
+  - 1.15.13
 before_script:
   - echo "deb https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/xUbuntu_18.04 /" | sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable.list
   - curl -L https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/xUbuntu_18.04/Release.key | sudo apt-key add -

Makefile

@@ -246,7 +246,7 @@ embed_bundle: clean cross $(HOST_BUILD_DIR)/crc-embedder check_bundledir $(HYPER
 
 .PHONY: update-go-version
 update-go-version:
-	./update-go-version.sh 1.14
+	./update-go-version.sh 1.15
 
 .PHONY: goversioncheck
 goversioncheck:

appveyor.yml

@@ -2,7 +2,7 @@ build: off
 clone_folder: c:\gopath\src\github.com\code-ready\crc
 environment:
   GOPATH: c:\gopath
-stack: go 1.14
+stack: go 1.15
 before_test:
   - choco install mingw
   - choco install make
@@ -12,7 +12,6 @@ before_test:
   - make cross
 test_script:
   - make test
-
 artifacts:
   - path: out\linux-amd64\crc
     name: crc linux executable

centos_ci.sh

@@ -3,7 +3,7 @@
 # bundle location
 BUNDLE_VERSION=4.7.13
 BUNDLE=crc_libvirt_$BUNDLE_VERSION.crcbundle
-GO_VERSION=1.14.13
+GO_VERSION=1.15.13
 
 # Output command before executing
 set -x

go.mod

@@ -1,6 +1,6 @@
 module github.com/code-ready/crc
 
-go 1.14
+go 1.15
 
 require (
 	github.com/Masterminds/semver/v3 v3.1.1

images/openshift-ci/Dockerfile

@@ -1,7 +1,7 @@
 # This Dockerfile is used by openshift CI
 # It builds an image containing crc and nss-wrapper for remote deployments, as well as the google cloud-sdk for nested GCE environments.
 
-FROM registry.svc.ci.openshift.org/openshift/release:golang-1.14 AS builder
+FROM registry.svc.ci.openshift.org/openshift/release:golang-1.15 AS builder
 WORKDIR /go/src/github.com/code-ready/crc
 COPY . .
 RUN make cross