build(deps): bump cffi from 1.14.3 to 1.14.4

Bumps [cffi](https://github.com/python-cffi/release-doc) from 1.14.3 to 1.14.4.
- [Release notes](https://github.com/python-cffi/release-doc/releases)
- [Commits](https://github.com/python-cffi/release-doc/commits)

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

Author: dependabot-preview[bot]

requirements-pinned.txt

@@ -1,5 +1,5 @@
 certifi==2020.6.20       # via requests
-cffi==1.14.3              # via cryptography, pynacl
+cffi==1.14.4              # via cryptography, pynacl
 chardet==3.0.4            # via requests
 cryptography==3.2.1         # via securesystemslib
 enum34==1.1.6             ; python_version < '3' # via cryptography