Add missing space

Author: tannewt

ports/zephyr-cp/cptools/cpbuild.py

@@ -150,7 +150,7 @@ async def run_command(
         # When on windows, use a responsefile if the command string is >= 8192
         if os.name == "nt" and len(command_string) >= 8192:
             responsefile.write_text("\n".join(command[1:]))
-            command_string = f"{command[0]}@{responsefile.name}"
+            command_string = f"{command[0]} @{responsefile.name}"
     else:
         command_string = command