Improve the ChEMBL drugs dataset

[stwhitfield]

Purpose: For datamol to have a dataset of all approved drugs in ChEMBL that contains metadata columns such as ChEMBL ID, date of approval, etc.

Changelogs

Added chembl_approved_drugs to datamol/data/
Modified dm.data.chembl_drugs() to leverage it
Adapted docstring to explain how it was generated
Modified unit tests
Added notebooks folder with code that generated chembl_approved_drugs.parquet

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Checklist:

• Was this PR discussed in an issue? It is recommended to first discuss a new feature into a GitHub issue before opening a PR.
• Add tests to cover the fixed bug(s) or the new introduced feature(s) (if appropriate).
• Update the API documentation if a new function is added, or an existing one is deleted.
• Write concise and explanatory changelogs below.
• If possible, assign one of the following labels to the PR: feature, fix or test (or ask a maintainer to do it for you).

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[codecov]

Codecov Report

Merging #214 (994ef96) into main (e3c4a38) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #214   +/-   ##
=======================================
  Coverage   91.91%   91.91%           
=======================================
  Files          46       46           
  Lines        3835     3835           
=======================================
  Hits         3525     3525           
  Misses        310      310           

Flag	Coverage Δ
unittests	91.91% <100.00%> (ø)

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Files	Coverage Δ
datamol/data/__init__.py	78.07% <100.00%> (ø)

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[hadim]

Thanks Shawn. As discussed in live, a few points below:

• Edit the original message in this ticket to add less details about the PR.
• Edit the docstring as discussed (dont mention medchem, markdown link to the notebook, date of the run, etc).
• Use Parquet instead of CSV.
• Apply black on the code.

[hadim]

Thanks @stwhitfield for your first contribution to datamol!