Add different os (ubuntu) to test and build

.github/workflows/go.yml

@@ -9,10 +9,12 @@ on:
 jobs:
 
   test:
-    runs-on: ubuntu-latest
+    name: Test on go ${{ matrix.go_version }} and ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         go_version: ['1.18', '1.17', '>=1.18']
+        os: [ubuntu-latest, ubuntu-20.04]
     steps:
     - uses: actions/checkout@v3
 
@@ -33,7 +35,11 @@ jobs:
 
   build:
     needs: test
-    runs-on: ubuntu-latest
+    name: Build on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, ubuntu-20.04]
     steps:
     - uses: actions/checkout@v3
     - name: Build