Dependency update request for performance improvements

[AbduSharif]

• If bullet is built with "-DBULLET2_MULTITHREADING=ON", multithreading support users can take advantage of async physics, it helps alot with modded setups and physics performance in general: https://openmw.readthedocs.io/en/latest/reference/modding/settings/physics.html#async-num-threads

• Using the OpenMW OSG fork (3.6 branch to be specific) should help when using the OpenMW distant land feature, and it has a few more optimizationa which should help with performance in general like using floats instead of doubles...etc (see commit history), it's also used for OpenMW 0.47 RCs: https://github.com/OpenMW/osg