Build with go 1.13.4 (#31)

Author: asvoboda

.circleci/config.yml

@@ -42,7 +42,7 @@ jobs:
     environment:
       TESTS_DIR: *results-dir
     docker:
-      - image: nmiyake/go:go-darwin-linux-1.11-t134
+      - image: circleci/golang:1.13.4-stretch
     steps:
       - checkout
       - *restore-godel-cache