fix: Fixes handling of recursive type aliases

[Daverball]

Closes #209

Handling of recursive type aliases was broken, since the symbol was registered lexicographically before where the use occurs. We've worked around this by using node.end_lineno and node.end_col_offset of the AnnAssign statement instead, which should be a little bit more robust.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.5%. Comparing base (966749f) to head (6a9293d).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #210     +/-   ##
=======================================
+ Coverage   96.4%   96.5%   +0.1%     
=======================================
  Files          4       4             
  Lines        968     968             
=======================================
+ Hits         934     935      +1     
+ Misses        34      33      -1     

Files with missing lines	Coverage Δ
flake8_type_checking/checker.py	96.2% <ø> (+0.1%)	⬆️

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