Do not test for 1.12.x and 1.13.x.

Author: Lucas Michot

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        go-version: [ 1.12.x, 1.13.x, 1.14.x, 1.15.x, 1.16.x ]
+        go-version: [ 1.14.x, 1.15.x, 1.16.x ]
 
     name: Go ${{ matrix.go-version }}