Require rdkit and default canonicalize in buy

[whitead]

It's almost always that case that you should canonicalize. Now that rdkit is on pypi, let's just make it default. Breaking change because now buy will default canonicalize and there are now dependencies.

Should address #31

[Copilot]

Pull Request Overview

This PR makes RDKit a required dependency and changes the default behavior of the buy function to canonicalize SMILES by default. This is a breaking change that bumps the version to 3.0.0.

• Makes RDKit a required dependency instead of optional
• Changes buy function default to canonicalize SMILES (canonicalize=True)
• Updates version to 3.0.0 across all relevant files

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
setup.py	Adds rdkit as a required dependency
molbloom/version.py	Updates version to 3.0.0
molbloom/bloom/bloom.h	Updates C header version constant to 3.0.0
molbloom/init.py	Changes buy function default canonicalize parameter to True

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[Jgmedina95]

now that rdkit is a dependency, it would make sense to add it a the top of the file, for best practices rather than locally, for the canon function. Other than that, everything seems fine.

[whitead]

good call - thanks