[update] add batch predicting for Gender model

deepface/models/demography/Gender.py

@@ -1,3 +1,6 @@
+# stdlib dependencies
+from typing import List
+
 # 3rd party dependencies
 import numpy as np
 
@@ -42,6 +45,24 @@ class GenderClient(Demography):
         # return self.model.predict(img, verbose=0)[0, :]
         return self.model(img, training=False).numpy()[0, :]
 
+    def predicts(self, imgs: List[np.ndarray]) -> np.ndarray:
+        """
+        Predict apparent ages of multiple faces
+        Args:
+            imgs (List[np.ndarray]): (n, 224, 224, 3)
+        Returns:
+            apparent_ages (np.ndarray): (n,)
+        """
+        # Convert list to numpy array
+        imgs_:np.ndarray = np.array(imgs)
+        # Remove redundant dimensions
+        imgs_ = imgs_.squeeze()
+        # Check if the input is a single image
+        if len(imgs_.shape) == 3:
+            # Add batch dimension
+            imgs_ = np.expand_dims(imgs_, axis=0)
+        return self.model.predict_on_batch(imgs_)
+
 
 def load_model(
     url=WEIGHTS_URL,