Upgrade Async Kit to 1.20.0

[PWrzesinski]

Currently Fluent SQLite driver silently depends on features (specifically the shutdownAsync function) introduced in Async Kit 1.20.0. That dependency is transient, without specifying Async Kit in the SQLite driver's Package.swift, causing a compilation error when an earlier version (like 1.19.0) is used.

It would probably be more correct to specifically add that dependency in the SQLite driver's Package.swift, but personally I don't see anything wrong with just updating it here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 24.43%. Comparing base (614d3ec) to head (dca918a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #621      +/-   ##
==========================================
- Coverage   24.78%   24.43%   -0.35%     
==========================================
  Files         149      149              
  Lines        8660     9353     +693     
==========================================
+ Hits         2146     2285     +139     
- Misses       6514     7068     +554     

see 81 files with indirect coverage changes

[gwynne]

Nice catch, thanks!