add support for go 1.12

Author: asahasrabuddhe

.github/workflows/echo.yml

@@ -27,7 +27,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: [1.13, 1.14, 1.15]
+        go: [1.12, 1.13, 1.14, 1.15]
     name: ${{ matrix.os }} @ Go ${{ matrix.go }}
     runs-on: ${{ matrix.os }}
     steps: