remove testing on 3.6

.travis.yml

@@ -34,11 +34,6 b' before_install:'
 install:
   - pip install pip --upgrade
   - pip install setuptools --upgrade
-  - if [[ "$TRAVIS_PYTHON_VERSION" == "3.6" ]]; then
-      echo "for the time being still test on 3.6";
-      sed -ibkp s/7/6/g setup.py;
-      git diff;
-    fi
   - pip install -e file://$PWD#egg=ipython[test] --upgrade
   - pip install trio curio --upgrade --upgrade-strategy eager
   - pip install 'pytest' 'matplotlib !=3.2.0'
@@ -73,9 +68,6 b' after_success:'
 matrix:
   include:
     - arch: amd64
-      python: "3.6"
-      dist: xenial
-    - arch: amd64
       python: "3.7"
       dist: xenial
     - arch: amd64