Adding tests for python 12, weekly (#8)

* add 3.12-dev CI tests

* add weekly build

Author: vassilyl

.github/workflows/CI.yml

@@ -5,14 +5,16 @@ on:
     branches: [ main ]
   pull_request:
     branches: [ main ]
+  schedule:
+  - cron: '30 09 * * 1'  # 9:30 every Monday
 
 jobs:
   build:
 
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11-dev']
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12-dev']
 
     steps:
     - uses: actions/checkout@v2