Add kubernetes version constraint and update version 1.20.1 in helm chart (#2901)

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

charts/fission-all/Chart.yaml

@@ -1,8 +1,9 @@
 apiVersion: v2
 name: fission-all
-version: v1.20.1-rc3
-appVersion: v1.20.1-rc3
+version: v1.20.1
+appVersion: v1.20.1
 description: Fission is a fast serverless framework for Kubernetes.
+kubeVersion: ">=1.23.0-0"
 home: https://fission.io/
 icon: https://fission.io/images/fission-logo-white.svg
 sources:
@@ -25,4 +26,4 @@ type: application
 annotations:
   artifacthub.io/signKey: |
     fingerprint: 2EAE29FDF8A387050C82CD5ABBDD4FD6A1FFCBF6
-    url: https://raw.githubusercontent.com/fission/fission-charts/main/public_key/pgp_keys.asc
+    url: https://raw.githubusercontent.com/fission/fission-charts/main/public_key/pgp_keys.asc