fix(xml): escape special chars from site_author (<managingEditor>)

[Guts]

Closes #360

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.23%. Comparing base (3e680e2) to head (ed9d8e8).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #401   +/-   ##
=======================================
  Coverage   80.23%   80.23%           
=======================================
  Files          11       11           
  Lines         779      779           
  Branches      130      130           
=======================================
  Hits          625      625           
  Misses        112      112           
  Partials       42       42           

Flag	Coverage Δ
unittests	80.23% <ø> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud