remove Swift 5 support

[swhitty]

Swift 6.3 nightlies are out so removing support for Swift 5.10 from this repo and only supporting last 4 versions;

Swift 6, 6.1, 6.2, 6,3

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.94%. Comparing base (f9d9a18) to head (0e511b5).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #183      +/-   ##
==========================================
+ Coverage   92.80%   92.94%   +0.14%     
==========================================
  Files          69       69              
  Lines        3446     3446              
==========================================
+ Hits         3198     3203       +5     
+ Misses        248      243       -5     

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