update go to 1.13

Signed-off-by: bblfsh-release-bot <release-bot@bblf.sh>

Dockerfile

@@ -32,7 +32,7 @@ FROM native as native_test
 #=================================
 # Stage 2: Go Driver Server Build
 #=================================
-FROM golang:1.12 as driver
+FROM golang:1.13 as driver
 
 ENV DRIVER_REPO=github.com/bblfsh/csharp-driver
 ENV DRIVER_REPO_PATH=/go/src/$DRIVER_REPO

README.md

@@ -1,11 +1,11 @@
-# C# driver for [Babelfish](https://github.com/bblfsh/bblfshd) ![Driver Status](https://img.shields.io/badge/status-beta-dbd25c.svg) [![Build Status](https://travis-ci.org/bblfsh/csharp-driver.svg?branch=master)](https://travis-ci.org/bblfsh/csharp-driver) ![Native Version](https://img.shields.io/badge/csharp%20version-2.1-aa93ea.svg) ![Go Version](https://img.shields.io/badge/go%20version-1.12-63afbf.svg)
+# C# driver for [Babelfish](https://github.com/bblfsh/bblfshd) ![Driver Status](https://img.shields.io/badge/status-beta-dbd25c.svg) [![Build Status](https://travis-ci.org/bblfsh/csharp-driver.svg?branch=master)](https://travis-ci.org/bblfsh/csharp-driver) ![Native Version](https://img.shields.io/badge/csharp%20version-2.1-aa93ea.svg) ![Go Version](https://img.shields.io/badge/go%20version-1.13-63afbf.svg)
 
 Development Environment
 -----------------------
 
 Requirements:
 - `docker`
-- Go 1.12+
+- Go 1.13+
 
 To initialize the build system execute: `go test ./driver`, at the root of the project. This will generate the `Dockerfile` for this driver.
 

build.yml

@@ -1,6 +1,6 @@
 sdk: '2'
 go-runtime:
-  version: '1.12'
+  version: '1.13'
 native:
   image: 'microsoft/dotnet:2.1-runtime'
   static: