fix(security): add localhost rule to default_proxy_filter

[WSH032]

Summary

Now, the default_proxy_filter will reject http://localhost.

Checklist

• I've read CONTRIBUTING.md.
• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.43%. Comparing base (558a86b) to head (a00bf76).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #50      +/-   ##
==========================================
+ Coverage   96.96%   97.43%   +0.46%     
==========================================
  Files           9        9              
  Lines         461      467       +6     
  Branches       44       36       -8     
==========================================
+ Hits          447      455       +8     
+ Misses          9        7       -2     
  Partials        5        5              

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