Updated solo_12_base.stl from open_robot_actuator_hardware

[thibnoel]

base_link mesh update

Description

The base_link mesh for the solo12 model was leading to a faulty collision behavior. It has been replaced by an updated version from https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware/mechanics/quadruped_robot_12dof_v1/stl_files_for_visualization/solo_12_base.STL

How I Tested

The collision behavior has been tested with 1 active collision par between the front left leg and the body using the FCL library, and the faulty collision is absent after the mesh update

Do not merge before

• [ ] link to dependent pull request

I fulfilled the following requirements

There is no new code in this PR

• [ ] All new code is formatted according to our style guide (for C++ run clang-format, for Python, run flake8 and fix all warnings).
• [ ] All new functions/classes are documented and existing documentation is updated according to changes.
• [ ] No commented code from testing/debugging is kept (unless there is a good reason to keep it).

[jviereck]

Thanks for copying over the fix and verifying the issue is fixed now @thibnoel !

Closes #19 .