Fix typo in predict docstring (#12076)

Author: EthicalCha0s

python-package/xgboost/core.py

@@ -2416,7 +2416,7 @@ def predict(
         strict_shape: bool = False,
     ) -> np.ndarray:
         """Predict with data.  The full model will be used unless `iteration_range` is
-        specified, meaning user have to either slice the model or use the
+        specified, meaning users have to either slice the model or use the
         ``best_iteration`` attribute to get prediction from best model returned from
         early stopping.