Set go requirements to >=1.13

Author: cmaglie

.travis.yml

@@ -5,7 +5,7 @@ os:
   - osx
 
 go:
-  - 1.12.x
+  - 1.13.x
 
 env:
   - GO111MODULE=on

README.md

@@ -61,7 +61,7 @@ See [Doing continuous integration with arduino builder](https://github.com/ardui
 
 ### Building from source
 
-You need [a recent version of Go (>=1.12.0)](https://golang.org/) that supports go modules.
+You need [a version of Go >=1.13.0](https://golang.org/).
 
 The project now uses `go.mod` for dependecy management, there is no need to `go get` anything or to set `GOPATH` env vars. The build is very simple:
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/arduino/arduino-builder
 
-go 1.12
+go 1.13
 
 require (
 	github.com/arduino/arduino-cli v0.0.0-20200212094638-c1dcf01822e9