ci/bare-metal: Reset colors at the end of a line of serial output.

We don't want the next line of our timestamp and other context to inherit
colors set by the serial command (visible with the new dEQP runner)

Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7434>

.gitlab-ci/bare-metal/serial_buffer.py

@@ -109,8 +109,8 @@ class SerialBuffer:
                     line = line.decode(errors="replace")
 
                     time = datetime.now().strftime('%y-%m-%d %H:%M:%S')
-                    print("{time} {prefix}{line}".format(
-                        time=time, prefix=self.prefix, line=line), flush=True, end='')
+                    print("{time} {prefix}{line}{endc}".format(
+                        time=time, prefix=self.prefix, line=line, endc='\033[0m'), flush=True, end='')
 
                     self.line_queue.put(line)
                     line = bytearray()