sagemathgh-39189: Add support for Python 3.13 in conda
    
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Fixes sagemath#39163

### 📝 Checklist

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- [x] The title is concise and informative.
- [ ] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

- sagemath#38749
- sagemath#39249

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URL: sagemath#39189
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik

Author: Release Manager

.github/workflows/ci-meson.yml

@@ -28,22 +28,24 @@ jobs:
       fail-fast: false
       matrix:
         os: ['ubuntu', 'macos', 'windows']
-        python: ['3.11', '3.12']
+        python: ['3.12', '3.13']
         tests: ['all']
         editable:
           ${{ fromJson(github.event_name == 'pull_request' && '[false]' || '[false, true]') }}
         include:
+          # One run for oldest supported Python
+          - os: 'ubuntu'
+            python: '3.11'
+            tests: 'all'
+          # Test only changed files
           - os: 'ubuntu'
             python: '3.12'
             tests: 'new'
-          # one additional editable run in pull_request, this has no effect if not pull_request
+          # One additional editable run in pull_request, this has no effect if not pull_request
           - os: 'ubuntu'
             python: '3.12'
             editable: true
             tests: 'all'
-          - os: windows
-            python: '3.13'
-            tests: 'all'
 
     steps:
       - uses: actions/checkout@v4