Add symforce python dependency

[henrywarhurst]

To fix this error I experienced during make px4_sitl:

-- cmake build type: RelWithDebInfo
-- ccache enabled via symlink (/usr/lib/ccache/c++ -> /usr/bin/ccache)
**/usr/bin/python3: Error while finding module specification for 'symforce.symbolic' (ModuleNotFoundError: No module named 'symforce')**
-- Could NOT find gz-transport (missing: gz-transport_DIR)
-- Found Java: /usr/bin/java (found version "1.8.0_292") 
-- ROMFS: ROMFS/px4fmu_common
Architecture:  amd64

[henrywarhurst]

@dagar I'm not sure the right person to tag here. You looked at a similar PR before so tagging you in.

[henrywarhurst]

I guess in light of PX4/PX4-Autopilot#20050 you maybe won't want to merge this. I don't think it hurts to add it in the devcontainer but that thinking may be mistaken

[henrywarhurst]

what're your thoughts @dagar?