Bump freezegun from 0.3.14 to 0.3.15

Bumps [freezegun](https://github.com/spulec/freezegun) from 0.3.14 to 0.3.15.
- [Release notes](https://github.com/spulec/freezegun/releases)
- [Changelog](https://github.com/spulec/freezegun/blob/master/CHANGELOG)
- [Commits](spulec/freezegun@0.3.14...0.3.15)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

dev-requirements.txt

@@ -14,7 +14,7 @@ dodgy==0.2.1  # Look for uploaded secrets
 flake8-commas==2.0.0  # Require silicon valley commas
 flake8-quotes==2.1.1  # Require single quotes
 flake8==3.7.9  # Lint
-freezegun==0.3.14
+freezegun==0.3.15
 isort==4.3.21  # Lint imports
 mypy==0.761  # Type checking
 pip-check-reqs-pip-gte-20==2.0.3.1