Add isort and black to travis/precommit

Author: nielstron

.pre-commit-config.yaml

@@ -0,0 +1,9 @@
+repos:
+  - repo: https://github.com/psf/black
+    rev: ''
+    hooks:
+      - id: black
+  - repo: https://github.com/pycqa/isort
+    rev: ''
+    hooks:
+      - id: isort

.travis.yml

@@ -1,24 +1,26 @@
 language: python
 
-python:
-  - "3.4"
-  - "3.5"
-  - "3.6"
-  - "3.7"
-dist: xenial
-sudo: true
-
 matrix:
+  include:
+    - python: '3.5'
+    - python: '3.6'
+    - python: '3.7'
+    - python: '3.8'
+      env: PRE_COMMIT=1
   fast_finish: true
+dist: xenial
+sudo: true
 
 install:
+  - test ! "$PRE_COMMIT" || pip install pre-commit
   - pip install pylint
   - pip install coverage
   - pip install coveralls
   # Check if installing works
   - pip install -e .
 
 script:
+  - test ! "$PRE_COMMIT" || pre-commit run --all-files
   # Check for import errors
   - coverage run --source=quantulum3 scripts/test_import_error.py
   # Build common words
@@ -44,7 +46,7 @@ deploy:
   provider: pypi
   on:
     branch: master
-    python: "3.7"
+    python: "3.8"
   distributions: "sdist bdist_wheel"
   skip_existing: true
   # Keep the generated classifier