CI: drop appveyor

.github/workflows/ci-testing.yml

@@ -44,7 +44,7 @@ jobs:
 
     - name: Tests
       run: |
-        coverage run --source gco -m pytest . -v --junitxml=junit/test-results-${{ runner.os }}-${{ matrix.python-version }}.xml
+        coverage run --source gco -m pytest . -v --doctest-modules --junitxml=junit/test-results-${{ runner.os }}-${{ matrix.python-version }}.xml
 
     - name: Try installing
       run: |

README.md

@@ -2,7 +2,6 @@
 
 ![CI testing](https://github.com/Borda/pyGCO/workflows/CI%20testing/badge.svg?branch=master&event=push)
 [![codecov](https://codecov.io/gh/Borda/pyGCO/branch/master/graph/badge.svg)](https://codecov.io/gh/Borda/pyGCO)
-[![Build status](https://ci.appveyor.com/api/projects/status/ovfsssqdb1c0xg0l?svg=true)](https://ci.appveyor.com/project/Borda/pygco)
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/4b875e6fbf3349e18a139a2a005736a4)](https://www.codacy.com/app/Borda/pyGCO?utm_source=github.com&utm_medium=referral&utm_content=Borda/pyGCO&utm_campaign=Badge_Grade)
 [![Coverage Badge](https://api.shippable.com/projects/5883a5e12a5d900f00b8b9ff/coverageBadge?branch=master)](https://app.shippable.com/github/Borda/pyGCO)
 [![Maintainability](https://api.codeclimate.com/v1/badges/9c11485e2f4f23189069/maintainability)](https://codeclimate.com/github/Borda/pyGCO/maintainability)