Boblight fix

- The default Boblight priority has been set to 128. If the sent priority differs from the default priority, it is registered (https://hyperion-project.org/threads/hyperion-ng-enigmalight-boblight-server.3558/#post-15006)
- Submodule flatbuffer updated to current master

Signed-off-by: Paulchen-Panther <16664240+Paulchen-Panther@users.noreply.github.com>

include/grabber/V4L2Grabber.h

@@ -105,7 +105,7 @@ private:
 	bool init();
 	void uninit();
 
-	void open_device();
+	bool open_device();
 
 	void close_device();