Fix send_file.py

Add a check for conn.recv(1024) to prevent the thread from blocking.

file_transfer/send_file.py

@@ -13,6 +13,8 @@ def send_file(filename: str = "mytext.txt", testing: bool = False) -> None:
         conn, addr = sock.accept()  # Establish connection with client.
         print(f"Got connection from {addr}")
         data = conn.recv(1024)
+        if not data:
+                break  #IF NOT data received,the Client has closed the Connection. 
         print(f"Server received: {data = }")
 
         with open(filename, "rb") as in_file: