Skip installation for linting step

Author: rhpvorderman

.github/workflows/ci.yml

@@ -34,8 +34,6 @@ jobs:
         uses: actions/setup-python@v2
       - name: Install tox
         run: pip install tox
-      - name: Install isal
-        run: sudo apt-get install libisal-dev
       - name: Build docs
         run: tox -e docs
   test:

tox.ini

@@ -25,6 +25,8 @@ commands=
 deps=flake8
      flake8-import-order
      mypy
+# Linting does not need the installed package.
+skip_install=true
 commands =
     flake8 src tests setup.py benchmark.py