Bump s3transfer from 0.14.0 to 0.15.0

Bumps [s3transfer](https://github.com/boto/s3transfer) from 0.14.0 to 0.15.0.
- [Changelog](https://github.com/boto/s3transfer/blob/develop/CHANGELOG.rst)
- [Commits](boto/s3transfer@0.14.0...0.15.0)

---
updated-dependencies:
- dependency-name: s3transfer
  dependency-version: 0.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -45,7 +45,7 @@ ldap3==2.9.1
 sqlparse==0.5.3
 
 # boto3 deps
-s3transfer==0.14.0
+s3transfer==0.15.0
 jmespath==1.0.1
 
 boto3>=1.9.198,<1.42.0