Remove pinned requests package

We currently pin requests to version 2.27.1. This was last bumped in
May of 2022 in 24808f0. Over time its
version has been incremented a few times.

Currently if you run tox you see an error like this:

> /home/runner/work/consumerfinance.gov/consumerfinance.gov/.tox/unittest/lib/python3.8/site-packages/requests/__init__.py:102: RequestsDependencyWarning: urllib3 (1.26.15) or chardet (5.1.0)/charset_normalizer (2.0.12) doesn't match a supported version!

For example, a recent GHA run:

https://github.com/cfpb/consumerfinance.gov/actions/runs/4737203702/jobs/8409716743

I'm not entirely sure why this started showing up now, but it seems to
have to do with psf/requests#6261.

Removing our requests pin seems to work fine.

requirements/libraries.txt

@@ -27,7 +27,6 @@ opensearch-py==1.1.0
 psycopg2-binary==2.8.6
 python-dateutil==2.8.2
 regdown==1.0.7
-requests==2.27.1
 requests-aws4auth==1.1.2
 s3transfer==0.5.2
 setuptools>=65.5.1