sitl_gazebo: update submodule

Includes:
- Fix for vibration on ground for standard_vtol.
- Noise for diff pressure / airspeed on Gazebo side.
- Fix for macOS magnetometer plugin linking error.

sitl_gazebo @ f13b91e5

-Subproject commit 0e43ddafa0c70a190a9080c17c9540d8f7ab5261
+Subproject commit f13b91e5756017a43ecdce1b574d17828c3e99bb