Install dev dependencies for CI tests

Author: samwelkanda

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install pipenv
-          pipenv install --dev
+          pipenv install --dev --skip-lock
       - name: Check code format
         run: |
           pipenv run yapf -dr .