Reformat Travis configuration

Author: Cito

.travis.yml

@@ -1,30 +1,30 @@
 language: python
 matrix:
   include:
-  - name: Code quality tests
-    env: TOXENV=black,flake8,mypy,docs
-    python: 3.7
-    dist: xenial
-    sudo: true
-  - name: Unit tests with Python 3.7
-    env: TOXENV=py37
-    python: 3.7
-    dist: xenial
-    sudo: true
-  - name: Unit tests with Python 3.6
-    env: TOXENV=py36
-    python: 3.6
+    - name: Code quality tests
+      env: TOXENV=black,flake8,mypy,docs
+      python: 3.7
+      dist: xenial
+      sudo: true
+    - name: Unit tests with Python 3.7
+      env: TOXENV=py37
+      python: 3.7
+      dist: xenial
+      sudo: true
+    - name: Unit tests with Python 3.6
+      env: TOXENV=py36
+      python: 3.6
 cache:
   directories:
-  - "$HOME/.cache/pip"
-  - "$TRAVIS_BUILD_DIR/.tox"
+    - "$HOME/.cache/pip"
+    - "$TRAVIS_BUILD_DIR/.tox"
 install:
-- pip install "poetry>=1.0.0a5"
-- poetry install
+  - pip install "poetry>=1.0.0a5"
+  - poetry install
 script:
-- tox -e $TOXENV -- --cov-report term-missing --cov=src
+  - tox -e $TOXENV -- --cov-report term-missing --cov=src
 after_success:
-- codecov
+  - codecov
 deploy:
   provider: pypi
   distributions: sdist bdist_wheel