chore(deps): bump cffi from 1.14.5 to 1.15.0

Bumps [cffi](http://cffi.readthedocs.org) from 1.14.5 to 1.15.0.

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

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

Author: dependabot[bot]

test/upstream-requirements-py27.txt

@@ -3,7 +3,7 @@ attrs==21.2.0
 backports.functools-lru-cache==1.6.4
 boto3==1.17.92
 botocore==1.20.92
-cffi==1.14.5
+cffi==1.15.0
 configparser==4.0.2
 contextlib2==0.6.0.post1
 coverage==5.5

test/upstream-requirements-py37.txt

@@ -1,7 +1,7 @@
 attrs==21.2.0
 boto3==1.17.92
 botocore==1.20.92
-cffi==1.14.5
+cffi==1.15.0
 coverage==5.5
 cryptography==3.4.7
 importlib-metadata==4.5.0