Disable "allow major version upgrade" on RDS instance

Author: waisingyiu

cdk/lib/__snapshots__/stack.test.ts.snap

@@ -635,7 +635,7 @@ Object {
       "DeletionPolicy": "Retain",
       "Properties": Object {
         "AllocatedStorage": "20",
-        "AllowMajorVersionUpgrade": true,
+        "AllowMajorVersionUpgrade": false,
         "AssociatedRoles": Array [
           Object {
             "FeatureName": "Lambda",

cdk/lib/stack.ts

@@ -105,7 +105,7 @@ export class PinBoardStack extends GuStack {
       allocatedStorage: 20, // minimum for GP2
       storageEncrypted: true,
       autoMinorVersionUpgrade: true,
-      allowMajorVersionUpgrade: true,
+      allowMajorVersionUpgrade: false,
       instanceType: ec2.InstanceType.of(
         ec2.InstanceClass.T4G,
         isPROD ? ec2.InstanceSize.SMALL : ec2.InstanceSize.MICRO