Remove unneeded pip install for python 2.7 on travis

Author: andyjack

.travis.yml

@@ -35,7 +35,6 @@ before_install:
 install:
   - pip install -r requirements.txt
   - pip install requests_mock pylint coveralls yapf
-  - "if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install ipaddr; fi"
 script:
   - coverage run --source=geoip2 setup.py test
   - "if [[ $TRAVIS_PYTHON_VERSION == '3.7' ]]; then ./.travis-pylint.sh; fi"