Fix osx-arm64 (M1) codesign issues

[Tobias-Fischer]

We now have builds for packages up to ros-galactic-desktop for osx-am64. However, to make things work, after installing/updating packages, one needs to run:

conda deactivate
find $CONDA_PREFIX -name "*.so" -exec codesign -s - -f {} \;
find $CONDA_PREFIX -name "*.dylib" -exec codesign -s - -f {} \;

As the signatures are not valid.

We are not sure whether this is an issue in RoboStack, Conda-forge, mamba, conda, ... so it's a bit hard to track down.

/cc @wolfv

[Tobias-Fischer]

Might be because of the newer compiler version that I used. It does not happen in ros-noetic where the old compiler is used. Hopefully fixed by #75

[KohlhardtC]

Running the command above did not work when the ros_galactic environment was active. The fix is to run conda deactivate before running the above commands to update the signatures.

[Tobias-Fischer]

This is not an issue anymore with the Python 3.9 builds :)