chore: remove unrequired pip pinning

Author: Midnighter

.travis.yml

@@ -28,8 +28,7 @@ matrix:
   fast_finish: true
 
 install:
-  - pip install "pip<19"
-  - pip install --upgrade setuptools wheel tox tox-travis
+  - pip install --upgrade pip setuptools wheel tox tox-travis
 
 script:
   - tox -- --cov-report=xml --cov-report=term
@@ -45,7 +44,6 @@ jobs:
   include:
     - stage: deploy
       install:
-        - pip install "pip<19"
         - pip install --upgrade pip setuptools wheel
       script: skip
       after_success: echo "Deploying..."