Google Cloud Spanner Migrations Runner

The `google-spanner-migrations-runner` package provides a robust engine for managing schema migrations in Google Cloud Spanner databases, supporting both Google-managed instances and the Spanner emulator. Currently at version 1.13.0, the library receives frequent updates, with minor versions and bug fixes typically released every few months. Unlike ORM-based migration tools, this runner operates directly with `.sql` files, emphasizing a 'migrations-as-code' approach where developers write and test their SQL scripts. It does not generate schema from application code. Key functionalities include applying migrations from a designated directory, validating SQL files, and maintaining a ledger of applied migrations to prevent re-execution. Migrations are applied transactionally and in a specific order, making file naming conventions crucial for successful database evolution. It also features optional annotations for environment-specific migration execution.