Update bcrypt requirement from <3.2,>=3.1 to >=3.1,<4.3

Updates the requirements on [bcrypt](https://github.com/pyca/bcrypt) to permit the latest version.
- [Changelog](https://github.com/pyca/bcrypt/blob/main/release.py)
- [Commits](pyca/bcrypt@3.1.0...4.2.0)

---
updated-dependencies:
- dependency-name: bcrypt
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -12,7 +12,7 @@ gevent==20.12.0  # http://www.gevent.org/changelog.html
 greenlet==1.0.0
 werkzeug>=0.16,<0.17  # https://github.com/pallets/werkzeug/blob/master/CHANGES
 patool>=1.12,<1.13  # https://github.com/wummel/patool/blob/master/doc/changelog.txt
-bcrypt>=3.1,<3.2  # https://github.com/pyca/bcrypt/
+bcrypt>=3.1,<4.3  # https://github.com/pyca/bcrypt/
 chardet>=3.0,<3.1  # https://pypi.python.org/pypi/chardet
 babel>=2.6,<2.7  # http://babel.pocoo.org/en/latest/changelog.html
 pyxdg>=0.26,<0.27  # https://freedesktop.org/wiki/Software/pyxdg/