fix: Upgrade aurora engine version to 11.16 (#471)

### Feature or Bugfix

- Bugfix


### Detail
Update Aurora engine version to 11.16. Fixes an issue where the Aurora
nested stack deployment in the data.all backend which goes to deployment
account would fail as AuroraPostgresEngineVersion.VER_10_18 is not
compatible with parameter group default.aurora-postgresql11
### Relates
- #466

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

deploy/stacks/aurora.py

@@ -120,7 +120,7 @@ def __init__(
             self,
             f'AuroraDatabase{envname}',
             engine=rds.DatabaseClusterEngine.aurora_postgres(
-                version=rds.AuroraPostgresEngineVersion.VER_10_18
+                version=rds.AuroraPostgresEngineVersion.VER_11_16
             ),
             deletion_protection=True,
             cluster_identifier=f'{resource_prefix}-{envname}-db',