Might as well test on all the supported Go versions

Author: benhoyt

.github/workflows/go.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        go: ['1.17', '1.13']
+        go: ['1.17', '1.16', '1.15', '1.14', '1.13']
 
     name: Go ${{ matrix.go }} Tests