ci: Use Python3.9 minimum

Author: pawamoy

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
     - name: Set up PDM
       uses: pdm-project/setup-pdm@v3
       with:
-        python-version: "3.8"
+        python-version: "3.9"
 
     - name: Resolving dependencies
       run: pdm lock -v
@@ -59,8 +59,6 @@ jobs:
         - macos-latest
         - windows-latest
         python-version:
-        - "3.7"
-        - "3.8"
         - "3.9"
         - "3.10"
         - "3.11"