Cache pre-commit, use tox-travis to simplify config, only coverage for non-lint

.travis.yml

@@ -1,5 +1,8 @@
 language: python
-cache: pip
+cache:
+  pip: true
+  directories:
+    - $HOME/.cache/pre-commit
 
 env:
   global:
@@ -18,29 +21,24 @@ matrix:
     - python: 3.8
       env: TOXENV=lint
     - python: 3.8
-      env: TOXENV=py38
     - python: 3.7
-      env: TOXENV=py37
     - python: 3.6
-      env: TOXENV=py36
     - python: 3.5
-      env: TOXENV=py35
     - python: pypy3
-      env: TOXENV=pypy3
-  allow_failures:
-    - env: TOXENV=pypy3
 
 install:
-- travis_retry pip install --upgrade pip
-- travis_retry pip install --upgrade tox
-- travis_retry pip install --upgrade coverage
+- travis_retry pip install -U pip
+- travis_retry pip install -U tox-travis
 
 script: tox
 
 after_success:
-- travis_retry pip install coveralls && coveralls
-- travis_retry pip install codecov && codecov
-- travis_retry pip install scrutinizer-ocular && ocular
+  - |
+    if [ "$TOXENV" != "lint" ]; then
+      travis_retry pip install -U coveralls && coveralls
+      travis_retry pip install -U codecov && codecov
+      travis_retry pip install -U scrutinizer-ocular && ocular
+    fi
 
 deploy:
   - provider: pypi