Updated tests to use connector syntax

[zumoshi]

Running tests gives deprecated warnings.

λ deno test --allow-env --allow-read --allow-net --allow-write
running 1 test from file:///.../denodb/tests/units/Relationships/foreignkey.test.ts
test MySQL: Foreign key test ...[denodb]: DEPRECATION warning, the usage with dialect instead of connector is deprecated and will be removed in future versions.
[denodb]: If you want to disable this warning pass `disableDialectUsageDeprecationWarning: true` with the dialect in the Database constructor.
[denodb]: If you want to migrate to the current behavior, visit https://github.com/eveningkid/denodb/blob/master/docs/v1.0.21-migrations/connectors.md for help
INFO connecting 127.0.0.1:3306
INFO connected to 127.0.0.1:3306
INFO close connection