Reject tool.thx.job with invalid keys

[lordmauve]

I accidentally typoed the requires key as needs (GitHub Actions has broken my brain).

This silently does nothing.

Expected behaviour

When parsing pyproject.toml, thx should warn about invalid keys in a table and discard the jog, e.g.

$ thx docs
WARNING: tool.thx.jobs.docs: unexpected key 'needs'; ignoring malformed job definition.
Usage: thx [OPTIONS] COMMAND1 [ARGS]... [COMMAND2 [ARGS]...]...
Try 'thx --help' for help.

Error: No such command 'docs'.