Bump python-coveralls from 2.7.0 to 2.9.3

Bumps [python-coveralls](https://github.com/z4r/python-coveralls) from 2.7.0 to 2.9.3.
- [Release notes](https://github.com/z4r/python-coveralls/releases)
- [Commits](https://github.com/z4r/python-coveralls/commits)

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

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

Author: dependabot[bot]

requirements/rtd.txt

@@ -17,7 +17,7 @@ py3dns==3.1.0
 mock==2.0.0
 pytest==2.9.1
 pytest-cov==2.2.1
-python-coveralls==2.7.0
+python-coveralls==2.9.3
 pep8==1.7.1
 git+https://github.com/SpamExperts/MINI-DNS-Server.git
 dnslib==0.9.16

requirements/tests.txt

@@ -2,7 +2,7 @@
 mock==2.0.0
 pytest==2.9.1
 pytest-cov==2.2.1
-python-coveralls==2.7.0
+python-coveralls==2.9.3
 pep8==1.7.1
 se_profile==1.0.0
 sqlalchemy==1.4.29