Bump pytest from 6.2.3 to 6.2.4

Bumps [pytest](https://github.com/pytest-dev/pytest) from 6.2.3 to 6.2.4.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.2.3...6.2.4)

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

requirements_dev.txt

@@ -4,7 +4,7 @@ wheel>=0.30.0
 # install requirements
 pyftpdlib==1.5.6
 PyOpenSSL==20.0.1
-pytest==6.2.3
+pytest==6.2.4
 
 # documentation
 Sphinx>=1.8