[github-actions] add BR --radio-version test (#7345)

tests/scripts/thread-cert/node.py

@@ -33,7 +33,6 @@ import logging
 import os
 import re
 import socket
-import string
 import subprocess
 import sys
 import time
@@ -883,6 +882,11 @@ class NodeImpl:
         self.send_command(cmd)
         self._expect_done()
 
+    def get_rcp_version(self) -> str:
+        self.send_command('rcp version')
+        rcp_version = self._expect_command_output()[0].strip()
+        return rcp_version
+
     def srp_server_get_state(self):
         states = ['disabled', 'running', 'stopped']
         self.send_command('srp server state')