Added pull request ref to build latest noobaa

Signed-off-by: Aayush Chouhan <[email protected]>

Author: achouhan09

.github/workflows/upgrade-tests.yaml

@@ -1,5 +1,5 @@
 name: Upgrade Tests
-on: [push, pull_request, workflow_dispatch]
+on: [pull_request]
 
 jobs:
   upgrade-tests:
@@ -35,6 +35,7 @@ jobs:
         with:
           repository: 'noobaa/noobaa-core'
           path: 'noobaa-core'
+          ref: ${{ github.event.pull_request.base.ref }}
 
       - name: Build noobaa (latest)
         run: |
@@ -79,8 +80,8 @@ jobs:
       - name: Upgrade noobaa to latest
         run: |
           cd ./noobaa-operator
-          VERSION=$(go run cmd/version/main.go)
-          ./build/_output/bin/noobaa-operator upgrade --noobaa-image='noobaa-core:upgrade-tests' --operator-image='noobaa/noobaa-operator:$VERSION'
+          OPERATOR_VERSION=$(go run cmd/version/main.go)
+          ./build/_output/bin/noobaa-operator upgrade --noobaa-image='noobaa-core:upgrade-tests' --operator-image='noobaa/noobaa-operator:$OPERATOR_VERSION'
 
       - name: Run Upgrade Tests
         run: |