Adds k8s 1.20 to EKS list

It also fixes the Cloud Formation template.
The template versions need to be wrapped around quotes,
since Yaml.safe_load will convert 1.20 to 1.2 otherwise.

Changelog: added

app/assets/javascripts/create_cluster/eks_cluster/constants.js

 export const DEFAULT_REGION = 'us-east-2';
 
 export const KUBERNETES_VERSIONS = [
-  { name: '1.15', value: '1.15' },
   { name: '1.16', value: '1.16' },
   { name: '1.17', value: '1.17' },
   { name: '1.18', value: '1.18' },
-  { name: '1.19', value: '1.19', default: true },
+  { name: '1.19', value: '1.19' },
+  { name: '1.20', value: '1.20', default: true },
 ];

vendor/aws/cloudformation/eks_cluster.yaml

@@ -7,13 +7,13 @@ Parameters:
   KubernetesVersion:
     Description: The Kubernetes version to install
     Type: String
-    Default: 1.19
+    Default: "1.20"
     AllowedValues:
-      - 1.15
-      - 1.16
-      - 1.17
-      - 1.18
-      - 1.19
+      - "1.16"
+      - "1.17"
+      - "1.18"
+      - "1.19"
+      - "1.20"
 
   KeyName:
     Description: The EC2 Key Pair to allow SSH access to the node instances