Improve constraints supports, fix bugs

[abondar]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks

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_{Comparing feature/constraints (1e8568e) with develop (30b55c5)}

[coveralls]

Pull Request Test Coverage Report for Build 22078837677

Details

• 251 of 316 (79.43%) changed or added relevant lines in 12 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.6%) to 83.285%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tortoise/migrations/schema_editor/oracle.py	36	38	94.74%
tortoise/migrations/schema_generator/state_diff.py	37	39	94.87%
tortoise/migrations/constraints.py	9	12	75.0%
tortoise/migrations/writer.py	12	15	80.0%
tortoise/migrations/schema_editor/base_postgres.py	15	20	75.0%
tortoise/migrations/schema_editor/base.py	33	39	84.62%
tortoise/migrations/schema_editor/sqlite.py	22	32	68.75%
tortoise/migrations/schema_editor/mysql.py	62	76	81.58%
tortoise/migrations/operations.py	17	37	45.95%

Files with Coverage Reduction	New Missed Lines	%
tortoise/migrations/operations.py	1	62.2%
tortoise/migrations/schema_editor/sqlite.py	1	55.77%

Totals
Change from base Build 22039557596:	0.6%
Covered Lines:	10958
Relevant Lines:	12690

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💛 - Coveralls