Make sam2 optional

[giswqs]

Some recent Colab updates break the sam2 installation. As a result, sam2 can no longer be installed. This PR makes sam2 an optional dependency.

[aruncveli]

Could this be related #394?

The fix for that seems to be limiting setuptools<75.9, according to JinsuaFeito-dev/segment-anything-2#1. Installing sam2 from local directory with that fix, then installing samgeo seems to work in Colab.

[giswqs]

@aruncveli Colab has setuptools v75.1.0 preinstalled, which meets setuptools<75.9. I just tested it with setuptools 75.8.2, and sam2 does not install.

[aruncveli]

Yes, sorry, I didn't test properly. Was randomly trying things to get the install to work.

I'd installed a patched version of sam2 from source, with the setuptools version constraint patched in that, before installing samgeo.

[aruncveli]

pip install segment-geospatial --no-build-isolation seems to succeed in Colab, since the build dependencies of everything in samgeo's requirements.txt (maybe just sam2/pytorch is relevant) are available in the Colab runtime.

[rbavery]

@giswqs just installing the different setuptools version won't work, you need to install sam2 from an isolated build with the new setuptools version (tested and confirmed working by me with uv) or install from my git commit. I've tested and this works, we're using it JinsuaFeito-dev/segment-anything-2#1

Once that PR is merged and a new sam2 release is made then you can pin to that new sam2 version

[giswqs]

The breaking changes introduced by setuptools have been reverted. If you upgrade setuptools to the latest version v0.78.0.2, sam2 can be installed now.
pypa/setuptools#4870 (comment)