Bugfix: Restrict shorter peg rounds to Archery tier as per the rules in the new 2025 field classifications.

[jatkinson1000]

Due to a lack of specific tests a last minute bug crept in to #46 whereby shorter peg rounds were not restricted to Archery classification , but instead had values returned for all classifications.

This patch rectifies that, and introduces tests explicitly for this that were previously missing.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.81%. Comparing base (29e2451) to head (b58b7da).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #101   +/-   ##
=======================================
  Coverage   97.81%   97.81%           
=======================================
  Files          30       30           
  Lines        1736     1742    +6     
=======================================
+ Hits         1698     1704    +6     
  Misses         38       38           

Files with missing lines	Coverage Δ
...utils/classifications/agb_field_classifications.py	100.00% <100.00%> (ø)
...cheryutils/classifications/tests/test_agb_field.py	100.00% <ø> (ø)