remove travis config file

.travis.yml.disable

@@ -1,21 +0,0 @@
-language: python
-python:
-  - "3.5"
-  - "3.6"
-  - "3.7"
-  - "3.8"
-dist: focal
-install:
-  - "pip install pip --upgrade"
-  - "pip install -r tests-requirements.txt"
-  - "pip install -r requirements.txt"
-  - "npm install -g remark-cli remark-validate-links"
-  - "npm install -g markdown-link-check"
-script:
-  ./tests.sh
-after_success:
-  coveralls
-env:
-  global:
-    - DOTDROP_FORCE_NODEBUG=
-    - DOTDROP_NOBANNER=