Update Python test matrix from 3.9 to 3.10

Agent-Logs-Url: https://github.com/microsoft/vscode-python/sessions/84bcccdc-ad5e-4bf0-8638-02ef16db88bf

Co-authored-by: rzhao271 <7199958+rzhao271@users.noreply.github.com>

Author: Copilot

.github/workflows/build.yml

@@ -174,7 +174,7 @@ jobs:
         # macOS runners are expensive, and we assume that Ubuntu is enough to cover the Unix case.
         os: [ubuntu-latest, windows-latest]
         # Run the tests on the oldest and most recent versions of Python.
-        python: ['3.9', '3.x', '3.13']
+        python: ['3.10', '3.x', '3.13']
 
     steps:
       - name: Checkout

.github/workflows/pr-check.yml

@@ -157,7 +157,7 @@ jobs:
         # macOS runners are expensive, and we assume that Ubuntu is enough to cover the Unix case.
         os: [ubuntu-latest, windows-latest]
         # Run the tests on the oldest and most recent versions of Python.
-        python: ['3.9', '3.x', '3.13'] # run for 3 pytest versions, most recent stable, oldest version supported and pre-release
+        python: ['3.10', '3.x', '3.13'] # run for 3 pytest versions, most recent stable, oldest version supported and pre-release
         pytest-version: ['pytest', 'pytest@pre-release', 'pytest==6.2.0']
 
     steps: