Fix linting issues for prospector 1.3.1 (#170)

Fix linting issues for prespector 1.3.1

Author: benjaoming

pre-commit-config.yaml

@@ -66,11 +66,14 @@ repos:
             .*/tests/.*|
             .*/migrations/.*
         )$
+      # Because of an issue with pylint's Django utils and PATH environment, we add PYTHONPATH.
+      # This was used as a hack when running on Circle CI as well
+      # Once we upgrade to prospector >=1.9, we can remove it again.
+      entry: env PYTHONPATH=readthedocs prospector
       # We have to install the dependencies from an URL since we don't have access to this file easily from pre-commit
       additional_dependencies:
         - -r
         - https://raw.githubusercontent.com/readthedocs/readthedocs.org/main/requirements/pip.txt
-        - flake8==3.8.4
 
 - repo: https://github.com/akaihola/darker
   rev: 1.3.2

prospector.yml

@@ -1,9 +1,11 @@
-strictness: medium
+strictness: low
 
 test-warnings: false
 doc-warnings: true
 
 uses:
+  # We have issues with FKs as strings and failure with astroid
+  # However, leaving out Django causes other linting issues
   - django
   - celery
 
@@ -26,11 +28,14 @@ pep8:
 
 pylint:
   options:
+    # Required for the Django plugin
+    django-settings-module: readthedocs.settings.test
     docstring-min-length: 20
     dummy-variables-rgx: '_$|__$|dummy'
     max-line-length: 100
   disable:
     # We do this for circular imports
+    - cyclic-import
     - import-outside-toplevel
     - inconsistent-return-statements
     # We need to adapt our isort config