Fix handling of executed migrations with the withDatetimeMicroseconds driver option

[roxblnfk]

🔍 What was changed

• Migrator::fetchMigrationData() passes created_at to the WHERE clause as a DateTimeInterface instead of a pre-formatted string, so the driver formats it exactly as it did on insert. Previously, with withDatetimeMicroseconds enabled, the stored value (...12:30:45.000000) never matched the lookup string (...12:30:45) on SQLite, so executed migrations were resolved as pending and re-run.
• The migration table's datetime columns are now declared with datetime(6). On SQL Server the legacy DATETIME type rejects values with six fractional digits, so with the option enabled even the bookkeeping insert failed; datetime2(6) accepts them.
• isConfigured() additionally compares the existing migration table with the declared schema, so tables created by previous versions are upgraded on configure().

How it works

• On SQL Server and Postgres the schema comparator detects the precision change and configure() alters the table once; the check then passes.
• MySQL and SQLite exclude column size from comparison, so existing tables keep their columns — both work with either datetime format as is.

Review notes

• Rows written while the option was toggled to a different value than the current one still won't match on SQLite (the stored text differs) — that pre-existing limitation is out of scope here.

Checklist

• Closes [Bug]: migrations does not works if driver option withDatetimeMicroseconds is ture #66
• How was this tested:
  • Unit tests added (fail on the previous behavior: SQLite failed all, SQL Server failed on insert)
  • Full test suites run locally against SQLite, MySQL, Postgres and SQL Server

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.33%. Comparing base (c1712b6) to head (7532343).

Files with missing lines	Patch %	Lines
src/Migrator.php	88.88%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x      #67      +/-   ##
============================================
+ Coverage     95.29%   95.33%   +0.04%     
- Complexity      248      250       +2     
============================================
  Files            30       30              
  Lines           786      793       +7     
============================================
+ Hits            749      756       +7     
  Misses           37       37              

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