Drop support for Helm 2 (apache#16575)

Helm 2 is EOL, so bump our chart to the v2 apiVersion

https://helm.sh/blog/helm-v2-deprecation-timeline/

.gitignore

@@ -204,8 +204,6 @@ log.txt*
 # Terraform variables
 *.tfvars
 
-Chart.lock
-
 # Chart dependencies
 **/charts/*.tgz
 

chart/Chart.yaml

@@ -15,23 +15,29 @@
 # specific language governing permissions and limitations
 # under the License.
 
-# apiVersion v1 is Helm 2
+# apiVersion v2 is Helm 3
 ---
-apiVersion: v1
+apiVersion: v2
 name: airflow
 version: 1.1.0-rc1
 appVersion: 2.1.0
 description: Helm chart to deploy Apache Airflow, a platform to
   programmatically author, schedule, and monitor workflows
 home: https://airflow.apache.org/
+sources:
+  - https://github.com/apache/airflow
 icon: https://airflow.apache.org/docs/apache-airflow/stable/_images/pin_large.png
 keywords:
   - apache
   - airflow
   - workflow
   - scheduler
+dependencies:
+  - name: postgresql
+    version: 6.3.12
+    repository: "https://charts.bitnami.com/bitnami"
+    condition: postgresql.enabled
 maintainers:
   - email: dev@airflow.apache.org
     name: Apache Airflow PMC
-sources:
-  - https://github.com/apache/airflow
+type: application

chart/README.md

@@ -31,7 +31,7 @@ cluster using the [Helm](https://helm.sh) package manager.
 ## Requirements
 
 - Kubernetes 1.14+ cluster
-- Helm 2.11+ or Helm 3.0+
+- Helm 3.0+
 - PV provisioner support in the underlying infrastructure (optionally)
 
 ## Features

chart/UPDATING.md

@@ -52,6 +52,10 @@ https://developers.google.com/style/inclusive-documentation
 
 The default Airflow version that is installed with the Chart is now ``2.1.0``, previously it was ``2.0.2``.
 
+### Helm 2 no longer supported
+
+This chart has dropped support for [Helm 2 as it has been deprecated](https://helm.sh/blog/helm-v2-deprecation-timeline/) and no longer receiving security updates since November 2020.
+
 ### Removed `dags.gitSync.root`, `dags.gitSync.dest`, and `dags.gitSync.excludeWebserver` parameters
 
 The `dags.gitSync.root` and `dags.gitSync.dest` parameters didn't provide any useful behaviors to chart users so they have been removed.

docs/helm-chart/index.rst

@@ -54,7 +54,7 @@ Requirements
 ------------
 
 -  Kubernetes 1.14+ cluster
--  Helm 2.11+ or Helm 3.0+
+-  Helm 3.0+
 -  PV provisioner support in the underlying infrastructure (optionally)
 
 Features