fix: Trailing useless bytes ignored while parsing PEM content

[dadrus]

Related issue(s)

closes #1562

Checklist

• I agree to follow this project's Code of Conduct.
• I have read, and I am following this repository's Contributing Guidelines.
• I have read the Security Policy.
• I have referenced an issue describing the bug/feature request.
• I have added tests that prove the correctness of my implementation.

Description

Fixes the referenced issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.58%. Comparing base (f8770b3) to head (17463ba).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1563   +/-   ##
=======================================
  Coverage   89.58%   89.58%           
=======================================
  Files         271      271           
  Lines        9084     9084           
=======================================
  Hits         8138     8138           
  Misses        702      702           
  Partials      244      244           

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