Bump cffi from 1.14.6 to 1.15.0 (#1465)

Bumps [cffi](http://cffi.readthedocs.org) from 1.14.6 to 1.15.0.

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -4,7 +4,7 @@ boto3==1.18.36
 botocore==1.21.62
 canonicaljson-rs==0.3.0
 certifi==2021.10.8
-cffi==1.14.6
+cffi==1.15.0
 chardet==4.0.0
 colander==1.8.3
 colorama==0.4.4