ci: remove prefer-lowest

Author: krissss

.github/workflows/run-tests.yml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest]
         php: [8.1, 8.2, 8.3]
-        stability: [prefer-lowest, prefer-stable]
+        stability: [prefer-stable]
 
     name: P${{ matrix.php }} - ${{ matrix.stability }} - ${{ matrix.os }}