Update to Go 1.13 to support Go modules out of the box

Author: g3force

.circleci/config.yml

@@ -21,7 +21,7 @@ jobs:
 
   backend:
     docker:
-      - image: circleci/golang:1.10
+      - image: cimg/go:1.13
     working_directory: /go/src/github.com/RoboCup-SSL/ssl-game-controller
     steps:
       - checkout
@@ -47,7 +47,7 @@ jobs:
 
   publish-github-release:
     docker:
-      - image: circleci/golang:1.10
+      - image: cimg/go:1.13
     steps:
       - attach_workspace:
           at: .

README.md

@@ -120,7 +120,7 @@ If you don't want to run the controller in real time, you can change the time ac
 
 ### Requirements
 You need to install following dependencies first: 
- * Go >= 1.10
+ * Go >= 1.13
  * Node
  * Yarn