Update go1.16 in github workflow

This commit updates golang version to 1.16 in github workflow files.

Author: atoato88

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up go
         uses: actions/setup-go@v2
         with:
-          go-version: 1.15
+          go-version: 1.16
           stable: true
 
       - run: |
@@ -39,7 +39,7 @@ jobs:
       - name: Set up go
         uses: actions/setup-go@v2
         with:
-          go-version: 1.15
+          go-version: 1.16
           stable: true
 
       - run: |
@@ -64,7 +64,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-go@v1
       with:
-        go-version: 1.15
+        go-version: 1.16
     - name: Install latest version of Kind
       run: |
         GO111MODULE=on go get sigs.k8s.io/kind