fix: invalid escape sequence error in regex pattern (#3902)
This PR fixes the "SyntaxError: invalid escape sequence" error in the
pydantic.py file. The issue was caused by the backslashes in the regular
expression pattern being treated as escape characters. By using a raw
string literal for the regex pattern (e.g., r"\{.*\}"), this fix ensures
that backslashes are treated as literal characters, thus preventing the
error.
Co-authored-by: Tomer Levy <tomer.levy@tipalti.com>
