Drop python 3.6 support and add 3.10

Author: RobbeSneyders

.github/workflows/python-test.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: ['3.7', '3.8', '3.9', '3.10']
         os: [windows-latest, ubuntu-latest]
       fail-fast: false
     steps:

.travis.yml

@@ -2,14 +2,14 @@ language: python
 sudo: false
 matrix:
   include:
-  - python: 3.6
-  - python: 3.7
-  - python: 3.8
-  - python: 3.9
-  - python: nightly
-  - python: pypy3
+  - python: '3.7'
+  - python: '3.8'
+  - python: '3.9'
+  - python: '3.10-dev'
+  - python: 'nightly'
+  - python: 'pypy3'
   allow_failures:
-  - python: nightly
+  - python: 'nightly'
 before_install:
 - python -m pip install --upgrade pip
 - pip install "poetry<1.2"