chore: add extension to temporary morph file

Author: ycexiao

tests/helper.py

@@ -1,13 +1,13 @@
 def create_morph_data_file(
     data_dir_path, x_morph, y_morph, x_target, y_target
 ):
-    morph_file = data_dir_path / "morph_data"
+    morph_file = data_dir_path / "morph_data.txt"
     morph_data_text = [
         str(x_morph[i]) + " " + str(y_morph[i]) for i in range(len(x_morph))
     ]
     morph_data_text = "\n".join(morph_data_text)
     morph_file.write_text(morph_data_text)
-    target_file = data_dir_path / "target_data"
+    target_file = data_dir_path / "target_data.txt"
     target_data_text = [
         str(x_target[i]) + " " + str(y_target[i]) for i in range(len(x_target))
     ]