tests

Added `ColumnType::Blob` #305

Job	Run time
Rustfmt	13s
Test	1m 4s
Clippy	55s
Check	47s
SQLite integration tests	3m 39s
MySQL integration tests	4m 29s
SQLite integration tests actix	4m 2s
Postgres integration tests	4m 16s
	19m 25s

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