px_uploader: catch serial exception correctly

Signed-off-by: Julian Oes <julian@oes.ch>

Tools/px_uploader.py

@@ -914,7 +914,7 @@ def main():
                         print(f"Found board id: {up.board_type},{up.board_rev} bootloader protocol revision {up.bl_rev} on {port}")
                         break
 
-                    except RuntimeError or serial.SerialException:
+                    except (RuntimeError, serial.SerialException):
 
                         if not up.send_reboot(args.use_protocol_splitter_format):
                             break
@@ -980,4 +980,4 @@ def main():
 if __name__ == '__main__':
     main()
 
-# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4
+# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4