Use only Python >3.8 now (#231)

Author: rocky

.github/workflows/ubuntu.yml

@@ -8,10 +8,10 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13']
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}