fix: drop redundant cast flagged by ty 0.0.85

[lesnik512]

Summary

ty 0.0.85 now infers the return type of FromDI as T_co, so the typing.cast there is redundant and ty reports it as a warning. That fails lint-ci in the scheduled run.

Closes #37

Changes

• Drop the redundant typing.cast in FromDI (modern_di_taskiq/main.py).

Checklist

• Lint and format pass (ruff)
• Type check passes (ty)
• Tests pass and new behavior is covered
• Build succeeds (uv build) if packaging or build config changed
• Repo metadata stays consistent across the three surfaces (GitHub description, pyproject description, profile blurb) if this touches packaging