Updated Go dependencies and added cache in workflows (#2099)

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

.github/workflows/push_pr.yaml

@@ -31,6 +31,11 @@ jobs:
         kindimage : [ 'kindest/node:v1.19.11','kindest/node:v1.20.7',  'kindest/node:v1.21.1' ]
         os: [ ubuntu-latest ] 
     steps:
+      - name: setup go
+        uses: actions/setup-go@v2.1.3
+        with:
+          go-version: "1.15.12"
+
       - name: Checkout sources
         uses: actions/checkout@v2.3.4
 
@@ -40,10 +45,12 @@ jobs:
           repository: fission/examples
           path: examples
 
-      - name: setup go
-        uses: actions/setup-go@v2.1.3
+      - uses: actions/cache@v2
         with:
-          go-version: "1.15.12"
+          path: ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
 
       - name: Helm installation
         uses: Azure/setup-helm@v1