[Issue 6663][helm] Lint the Helm chart in the CI (apache#6666)

### Motivation

Prevent issues such as apache#6663 by checking the validity of the Helm chart in the CI.

### Modifications

Add a GitHub Actions workflow checking the chart.

.github/workflows/ci-deployment-helm.yaml

@@ -0,0 +1,41 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+name: CI - Deployment - Helm
+on:
+  pull_request:
+    branches:
+      - master
+
+jobs:
+
+  helm:
+    name:
+    runs-on: ubuntu-latest
+    timeout-minutes: 120
+
+    steps:
+      - name: checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: Lint the Helm chart
+        run: helm lint deployment/kubernetes/helm/pulsar