CI: drop unsupported Python versions.

Author: greenrobot-team

.github/workflows/test.yaml

@@ -9,8 +9,8 @@ jobs:
     strategy:
       fail-fast: false # To see all versions that fail.
       matrix:
-        os: [ubuntu, windows, macos]
-        python: [3.5, 3.6, 3.7, 3.8, 3.9]
+        os: ["ubuntu", "windows", "macos"]
+        python: ["3.7", "3.8", "3.9", "3.10"] # https://devguide.python.org/versions/#versions
 
     runs-on: ${{ matrix.os }}-latest
 

.gitlab-ci.yml

@@ -38,10 +38,6 @@ build:
   extends: .test
   tags: [x64, docker, linux]
 
-test:linux:x64:3.6:
-  extends: .test:linux:x64
-  image: python:3.6
-
 test:linux:x64:3.7:
   extends: .test:linux:x64
   image: python:3.7