build(deps): bump cffi from 1.15.0 to 1.15.1

Bumps [cffi](http://cffi.readthedocs.org) from 1.15.0 to 1.15.1.

---
updated-dependencies:
- dependency-name: cffi
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements-pinned.txt

@@ -1,4 +1,4 @@
-cffi==1.15.0              # via cryptography, pynacl
+cffi==1.15.1              # via cryptography, pynacl
 colorama==0.4.5
 cryptography==37.0.3
 pycparser==2.21           # via cffi