build(deps): add ot-literature as a git dependency

[d0choa]

Summary

The new literature_* pyspark steps in #113 import from the literature package (e.g. from literature.dataset.match_mapped import MatchMapped), but no such dependency is declared. Without this, the steps fail at import time with ModuleNotFoundError. This PR adds ot-literature as a git dependency, mirroring the pattern used for clinical-mining.

Changes

• pyproject.toml:
  • Add ot-literature to [project].dependencies
  • Add [tool.uv.sources] block pointing at opentargets/ot-literature, branch = "dev"
  • Map the distribution name ot-literature to the import name literature for deptry
• uv.lock: a uv lock against dev is currently not possible (see below). The lockfile in this PR was generated against a temporary branch that has the same content as dev plus the pyspark fix; it will need to be regenerated against dev once the upstream blockers below are resolved.

Blockers on ot-literature dev

uv lock against branch = "dev" fails today:

× No solution found ...
  ot-literature==0.1.0 depends on pyspark==3.3.4
  pts depends on pyspark==3.5.7
  → unsatisfiable

In addition, even after the pyspark conflict is resolved, runtime imports will still fail because dev does not yet contain match_mapped.py (used by literature_cooccurrence). Both are tracked upstream:

• pyspark conflict — ot-literature#7, targeting dev. Merging it removes the resolver conflict.
• match_mapped etc. — currently only on the vh-restructure-datasets branch in ot-literature; needs to merge into dev for runtime imports to succeed.

Once both have landed on dev, run uv lock from this branch and force-push to refresh the lockfile.

Heads-up: transitive dev deps

ot-literature declares pytest and ipykernel in its top-level dependencies (rather than under a dev/optional group), so they will end up in pts's runtime closure. Pre-existing issue in ot-literature; out of scope here.

Test plan

• Once ot-literature dev has both fixes, uv lock resolves cleanly and uv sync succeeds.
• uv run pts -h succeeds.
• uv run pts --step literature_publication (or similar) imports without ModuleNotFoundError.