ci: build/test with multiple version of go (google#945)

Signed-off-by: Carlos Panato <[email protected]>

Author: cpanato

.github/workflows/knative-go-build.yaml

@@ -27,7 +27,7 @@ jobs:
     name: Build
     strategy:
       matrix:
-        go-version: [1.15.x]
+        go-version: ['1.15.x', '1.16.x']
         platform: [ubuntu-latest]
 
     runs-on: ${{ matrix.platform }}

.github/workflows/knative-go-test.yaml

@@ -31,7 +31,7 @@ jobs:
     name: Unit Tests
     strategy:
       matrix:
-        go-version: [1.15.x]
+        go-version: ['1.15.x', '1.16.x']
         platform: [ubuntu-latest]
 
     runs-on: ${{ matrix.platform }}