fixes trailing slash issue with custom board path.

Author: kdschlosser

make.py

@@ -264,6 +264,9 @@ def create_lvgl_header():
     get_submodules()
 
     if custom_board_path is not None:
+        if custom_board_path.endswith('/'):
+            custom_board_path = custom_board_path[:-1]
+
         board_name = os.path.split(custom_board_path)[-1]
         dst_path = f'lib/micropython/ports/{target}/boards/{board_name}'
         if os.path.exists(dst_path):