Don't install in local virtual env before running pylint

Author: hardbyte

.github/workflows/ci.yml

@@ -71,7 +71,6 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -e .
         pip install -r requirements-lint.txt
     - name: mypy 3.7
       run: |