[stable/airflow] proper initializatons of variables for airflow chart (#17132)

* proper initializatons of variables

* `ingress.web.annotations` and `ingress.flower.annotations` should be initialized as maps
* `dags.git.secret` should be initialized as empty string

Signed-off-by: Tin Kyaw <tin@lsvp.com>

* bumped version to 4.0.9

Signed-off-by: Tin Kyaw <tin@lsvp.com>

stable/airflow/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 description: Airflow is a platform to programmatically author, schedule and monitor workflows
 name: airflow
-version: 4.0.8
+version: 4.0.9
 appVersion: 1.10.4
 icon: https://airflow.apache.org/_images/pin_large.png
 home: https://airflow.apache.org/

stable/airflow/values.yaml

@@ -294,7 +294,7 @@ ingress:
     ## Annotations for the webserver
     ## Airflow webserver handles relative path completely, just let your load balancer give the HTTP
     ## header like the requested URL (no special configuration neeed)
-    annotations:
+    annotations: {}
       ##
       ## Example for Traefik:
       # traefik.frontend.rule.type: PathPrefix
@@ -357,7 +357,7 @@ ingress:
     ##              }
     ##            }
     ## ==== IF YOU HAVE FLOWER > JANUARY 2018, NO MORE NEED TO STRIP THE PREFIX ====================
-    annotations:
+    annotations: {}
       ##
       ## NOTE: it is important here to have your reverse proxy strip the path/rewrite the URL
       ## Example for Traefik:
@@ -443,7 +443,7 @@ dags:
     ## branch name, tag or sha1 to reset to
     ref: master
     ## pre-created secret with key, key.pub and known_hosts file for private repos
-    secret: {}
+    secret: ""
   initContainer:
     ## Fetch the source code when the pods starts
     enabled: false