ci: enable workflow dispatch for helm test (#893)

Signed-off-by: Jeffrey Tang <jeffrey@swirldslabs.com>

.github/workflows/zxc-helm-chart-tests.yaml

@@ -20,6 +20,7 @@ name: "ZXC: FS Helm Chart Tests"
 # - .github/workflows/flow-pull-request-checks.yaml
 
 on:
+  workflow_dispatch:
   workflow_call:
     inputs:
       custom-job-label:
@@ -96,6 +97,11 @@ jobs:
             echo ">> No relevant files are changed. No need to run helm chart tests"
           fi
 
+      - name: Workflow trigger
+        if: github.event_name == 'workflow_dispatch'
+        run: |
+          echo "run-tests=true" >> "${GITHUB_OUTPUT}"
+
       - name: Initialize Job Variables
         id: vars
         if: ${{ steps.check-changed-files.outputs.run-tests && !cancelled() && !failure() }}