feat(neptune): add engine version 1.0.5.0 (#16394)

Add AWS Neptune engine versions 1.0.5.0.
https://docs.aws.amazon.com/neptune/latest/userguide/engine-releases-1.0.5.0.html

Closes #16388.

Deployment successfully testet:
```ts
new neptune.DatabaseCluster(this, 'Database', {
  vpc,
  instanceType: neptune.InstanceType.T3_MEDIUM,
  engineVersion: neptune.EngineVersion.V1_0_5_0,
});
```


----

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

packages/@aws-cdk/aws-neptune/lib/cluster.ts

@@ -46,6 +46,10 @@ export class EngineVersion {
    * Neptune engine version 1.0.4.1
    */
   public static readonly V1_0_4_1 = new EngineVersion('1.0.4.1');
+  /**
+   * Neptune engine version 1.0.5.0
+   */
+  public static readonly V1_0_5_0 = new EngineVersion('1.0.5.0');
 
   /**
    * Constructor for specifying a custom engine version