fix: restore missing indentation in anonymise_pdf function body

[boscorat]

Summary

The retain_descriptions parameter addition in d09e01c lost the 4-space indentation of the function body in anonymise.py, placing the if/return statements at module level. This causes a SyntaxError: 'return' outside function on any import of bank_statement_parser.

Root cause

Copilot Autofix mangled the indentation when adding the retain_descriptions parameter to the function body.

Fix

Restored proper 4-space indentation for lines 110-120 (the if guard and return statement).

Testing

• ruff check and ruff format --check pass
• The file is now valid Python and importable