Improve wording

src/setup-python.ts

@@ -55,7 +55,7 @@ async function run() {
       }
     } else {
       core.warning(
-        'python-version is empty, the OS native python will be used'
+        "Step input 'python-version' is not set, the OS native python version will be used"
       );
     }
     const matchersPath = path.join(__dirname, '../..', '.github');