Adopt Async APIs

[0xTim]

Fixes an issue where Fluent SQLite would hang, especially when installing the NIO Event Loop executor.

Drops support for Swift 5.8

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.69%. Comparing base (9cc162d) to head (a10f320).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #98      +/-   ##
==========================================
- Coverage   82.46%   81.69%   -0.78%     
==========================================
  Files           7        7              
  Lines         211      213       +2     
==========================================
  Hits          174      174              
- Misses         37       39       +2     

Files with missing lines	Coverage Δ
...ources/FluentSQLiteDriver/FluentSQLiteDriver.swift	66.66% <100.00%> (-6.07%)	⬇️
...rces/FluentSQLiteDriver/SQLiteError+Database.swift	95.23% <ø> (ø)