Fix deprecation warnings due to invalid escape sequences.

[tirkarthi]

Fixes #409

[jorenham]

@DenisCarriere Would you mind merging this? It is but a one-liner.

[DavidMertz]

I am experiencing the same issue, with Python 3.12. I utilize usaaddress-scourgify which included gocoder as a dependency. Running a FastAPI server that utilizes this, I've recently seen:

% uv run uvicorn app.main:app --reload
INFO:     Will watch for changes in these directories: ['/home/dmertz/git/SEIU/ada-etl']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [214130] using WatchFiles
/home/dmertz/git/SEIU/ada-etl/.venv/lib/python3.12/site-packages/geocoder/uscensus.py:36: SyntaxWarning: invalid escape sequence '\d'
  match = re.search('^\d+', self.address, re.UNICODE)

I'm not sure why I've seen this syntax warning only recently. Perhaps it got promoted to SyntaxWarning. I think I just recently updated by 3.12.7 from an earlier 3.12, which might have added more checks.

I'd love it if the merge can be made.