examples: bump module version to 0.12.0

[ilian]

Fixes HTTP 400 errors when applying resources in the examples/ directory.

Fixed errors

│ Error: creating RDS DB Instance (metaflowmetaflow40yrvx6i): InvalidParameterCombination: RDS does not support creating a DB instance with the following combination: DBInstanceClass=db.t2.small, Engine=postgres, EngineVersion=11.22, LicenseModel=postgresql-license. For supported combinations of instance class and database engine version, see the documentation.
│       status code: 400, request id: 40e6e5bb-d95b-47b4-82b8-6b8dc506fc56
│
│   with module.metaflow-datastore.aws_db_instance.this[0],
│   on .terraform/modules/metaflow-datastore/modules/datastore/rds.tf line 98, in resource "aws_db_instance" "this":
│   98: resource "aws_db_instance" "this" {
│
╵
╷
│ Error: creating Lambda Function (metaflowdb_migrate40yrvx6i): operation error Lambda: CreateFunction, https response error StatusCode: 400, RequestID: 445a5bf5-0256-4ab3-a5fe-edfe8029af0b, InvalidParameterValueException: The runtime parameter of python3.7 is no longer supported for creating or updating AWS Lambda functions. We recommend you use the new runtime (python3.12) while creating or updating functions.
│
│   with module.metaflow-metadata-service.aws_lambda_function.db_migrate_lambda,
│   on .terraform/modules/metaflow-metadata-service/modules/metadata-service/lambda.tf line 115, in resource "aws_lambda_function" "db_migrate_lambda":
│  115: resource "aws_lambda_function" "db_migrate_lambda" {
│