fix(publish-helm-chart): skip plugin verification for helm v4 compat (#111)

Helm v4.1.4 (installed by default since #106) verifies plugin sources on
`helm plugin install`. The chartmuseum/helm-push plugin does not ship a
verification manifest, so the install fails with:

    Error: plugin source does not support verification. Use --verify=false
    to skip verification

Pass `--verify=false` explicitly. The flag is accepted (as a no-op) on v3,
so callers pinning `helm-version: v3.x` are unaffected.

Broke nightly head-chart publish for loft-enterprise (and any other
caller using publish-helm-chart/v1).

Author: sydorovdmytro

.github/workflows/publish-helm-chart.yaml

@@ -99,7 +99,10 @@ jobs:
           version: ${{ inputs.helm-version }}
 
       - name: Install helm-push plugin
-        run: helm plugin install https://github.com/chartmuseum/helm-push.git
+        # --verify=false: Helm v4 verifies plugin sources by default; the
+        # chartmuseum/helm-push plugin does not ship a verification manifest,
+        # so the install fails without this flag. The flag is a no-op on v3.
+        run: helm plugin install --verify=false https://github.com/chartmuseum/helm-push.git
 
       - name: Set up yq
         uses: dcarbone/install-yq-action@4075b4dca348d74bd83f2bf82d30f25d7c54539b # v1.3.1