Try upgrade pip in before_install step

Author: Chris Jackson

.travis.yml

@@ -15,9 +15,9 @@ env:
   - DJANGO_INSTALL=django\<2.1.99
   - DJANGO_INSTALL=git+https://github.com/django/django.git\#egg=django
 # command to install dependencies (mock & nose are already installed)
+before_install:
+  - python -m pip install --upgrade pip
 install:
-  - pip install --upgrade pip
-  - pip --version
   - pip install $DJANGO_INSTALL
   - python setup.py install
   - pip install django-nose coverage mock