Remove travis-ci config

It's not used

.travis.yml

@@ -1,15 +0,0 @@
-matrix:
-  include:
-    - os: linux
-      dist: xenial
-      language: python
-      python: "3.7"
-
-install:
-  - python -m pip install --upgrade setuptools
-  - python -m pip install --upgrade pytest flake8 mypy flask requests
-
-script:
-  - python -m pytest .
-  - python -m flake8 .
-  - python -m mypy .