Fix: Correct slice index calculation in ApplyXMLMixin

[pyob-bot]

Summary of Changes

Updated the slice index calculation in src/pyob/xml_mixin.py to use search_lines_stripped instead of search_lines when calculating the end index for code replacement. This ensures that the slice correctly accounts for the length of the stripped lines, preventing potential index misalignment during code modification.

Technical Impact

• Correctness: Resolves an off-by-one or length mismatch error that could occur when the length of the stripped search lines differs from the original search lines.
• Stability: Improves the reliability of the XML-based code patching mechanism by ensuring the replacement logic accurately targets the intended block of code.