bump Dart SDK min version

[sensuikan1973]

No description provided.

[sensuikan1973]

https://pub.dev/packages/ffigen/changelog#1900

Breaking change: Major change to the way ObjC methods are code-genned. Methods now use named parameters, making them more readable and closer to how they're written in ObjC. For example, the NSData method dataWithBytes:length: used to be generated as dataWithBytes_length_(Pointer bytes, int length), but is now generated as dataWithBytes(Pointer bytes, {required int length}). Protocol methods are not affected.
Migration tip: A quick way to find affected methods is to search for _(.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.41%. Comparing base (e444f7c) to head (620c123).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #767      +/-   ##
==========================================
+ Coverage   96.39%   96.41%   +0.01%     
==========================================
  Files          15       15              
  Lines         666      669       +3     
==========================================
+ Hits          642      645       +3     
  Misses         24       24              

Flag	Coverage Δ
macos-latest	96.26% <100.00%> (+0.01%)	⬆️
ubuntu-latest	96.11% <100.00%> (+0.01%)	⬆️
unit_test	96.41% <100.00%> (+0.01%)	⬆️
windows-latest	96.41% <100.00%> (+0.01%)	⬆️

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Files with missing lines	Coverage Δ
lib/src/board.dart	100.00% <100.00%> (ø)
lib/src/ffi/dylib_utils.dart	90.00% <100.00%> (+2.50%)	⬆️
lib/src/position.dart	96.66% <100.00%> (+0.11%)	⬆️

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