Support Django4

Merge pull request #631 from timgates42/bugfix_typo_similar

docs: Fix simple typo, similiar -> similar

v1.9.0

Added custom tenant strategies by refactoring a BaseTenantMiddleware to allow greater control over the method used for determining the active tenant.

Parallel execution of database migrations using ParallelExecutor.

Added codes to check framework warnings and errors.

Documentation improvements and updating example projects and tutorials for recent versions of Django.