Update go tests to 1.16.

PiperOrigin-RevId: 381944519

Author: Matt LaPlante

.github/workflows/go_tests.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: 1.14.x
+          go-version: 1.16.x
 
       - name: Check out code into the Go module directory
         uses: actions/checkout@v2