Merge pull request #74 from dokku/upgrade-builder

Upgrade ci builder to ubuntu 20.04

Author: josegonzalez

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ on:
 jobs:
   build:
     name: build
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       fail-fast: true