Up Swift Version to 5.8

[fpseverino]

These changes are now available in 4.4.0

• Update to latest version of LeafKit to support time zones in #date tag.
• Update to latest version of Vapor.
• Set the minimum supported Swift version to 5.8

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.16%. Comparing base (e7c3157) to head (f6cdbe8).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #233      +/-   ##
==========================================
+ Coverage   68.44%   69.16%   +0.72%     
==========================================
  Files           5        5              
  Lines         263      240      -23     
==========================================
- Hits          180      166      -14     
+ Misses         83       74       -9     

see 5 files with indirect coverage changes

[0xTim]

I would say this isn't hugely needed - however you can bump the tools version to 5.8 as we should do that anyway

[0xTim]

Thanks!