Github workflows use go version from go.mod (#1146)

Author: waciumawanjohi

.github/workflows/upgrade-test.yaml

@@ -32,7 +32,8 @@ jobs:
 
       - name: set up Go
         uses: actions/setup-go@v3
-        with: {go-version: '^1.18'}
+        with:
+          go-version-file: 'go.mod'
 
       - name: setup base dependencies
         run: |-

.github/workflows/validation.yaml

@@ -36,7 +36,8 @@ jobs:
 
       - name: set up Go
         uses: actions/setup-go@v3
-        with: {go-version: '^1.18'}
+        with:
+          go-version-file: 'go.mod'
 
       - name: setup carvel tooling binaries
         uses: vmware-tanzu/carvel-setup-action@v1