chore(enum-updater): exclude none enum value for appsync AppSyncDataSourceType enum (aws#34409)

### Reason for this change

`NONE` should not be a supported enum value in CDK

### Description of changes
Exclude`NONE` enum value for appsync `AppSyncDataSourceType` enum

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: paulhcsun

tools/@aws-cdk/enum-updater/lib/exclude-values.json

@@ -1,4 +1,10 @@
 {
+    "appsync": {
+        "AppSyncDataSourceType": {
+            "values": ["NONE"],
+            "comment": "NONE is not supported"
+        }
+    },
     "codebuild": {
         "FleetComputeType": {
             "comment": "They values are already defined in a different place"