Django-pg-zero-downtime-migrations

- changed `ADD COLUMN DEFAULT NULL` to safe operation for code default
- changed `ADD COLUMN DEFAULT NOT NULL` to safe operation for `db_default` in django 5.0+
- added `ZERO_DOWNTIME_MIGRATIONS_KEEP_DEFAULT` settings and changed `ADD COLUMN DEFAULT NOT NULL` with this settings to safe operation for django<5.0
- added `ZERO_DOWNTIME_MIGRATIONS_EXPLICIT_CONSTRAINTS_DROP` settings and added dropping constraints and indexes before drop column or table
- fixed sqlmigrate in idempotent mode
- fixed creation unique constraint with include parameter
- fixed idempotent mode tests
- updated unsafe migrations links to documentation
- updated patched code to latest django version
- updated test image to ubuntu 24.04
- improved README

- added idempotent mode and `ZERO_DOWNTIME_MIGRATIONS_IDEMPOTENT_SQL` setting
- fixed django 3.2 degradation with missing `skip_default_on_alter` method
- improved readme
- updated release github action

- fixed deferred sql errors
- added django 5.0 support
- added python 3.12 support
- added postgres 16 support
- drop postgres 11 support
- drop `ZERO_DOWNTIME_MIGRATIONS_USE_NOT_NULL` setting
- marked `migrate_isnotnull_check_constraints` command deprecated

- added django 4.2 support
- marked django 3.2 support deprecated
- marked django 4.0 support deprecated
- marked django 4.1 support deprecated
- marked postgres 11 support deprecated
- drop postgres 10 support
- updated test docker image to ubuntu 22.04

- added `serial` and `integer`, `bigserial` and `bigint`, `smallserial` and `smallint`, same types changes as safe migrations
- fixed `AutoField` type changing and concurrent insertions issue for `django<4.1`
- added sequence dropping and creation timeouts as they can be used with `CASCADE` keyword and affect other tables
- added django 4.1 support
- added python 3.11 support
- added postgres 15 support
- marked postgres 10 support deprecated
- drop django 2.2 support
- drop django 3.0 support
- drop django 3.1 support
- drop postgres 9.5 support
- drop postgres 9.6 support
- add github actions checks for pull requests

- fixed rename model with keeping `db_table` raises `ALTER_TABLE_RENAME` error 26
- added django 3.2 support
- added django 4.0 support
- added python 3.9 support
- added python 3.10 support
- added postgres 14 support
- marked django 2.2 support deprecated
- marked django 3.0 support deprecated
- marked django 3.1 support deprecated
- marked python 3.6 support deprecated
- marked python 3.7 support deprecated
- marked postgres 9.5 support deprecated
- marked postgres 9.6 support deprecated
- move to github actions for testing