Update golang Docker tag to v1.13 (#24)

renovate[bot] · techknowlogick · commit 697cf45591d6 · 2019-11-18T13:22:59.000-05:00
diff --git a/.drone.yml b/.drone.yml
@@ -7,7 +7,7 @@ workspace:
 
 steps:
 - name: fetch-and-test
-  image: golang:1.12
+  image: golang:1.13
   environment:
     GO111MODULE: on
   commands:
