chore: delete deprecated code

[joanise]

Now that we've release g2p 2.0, we can simply delete all the code to accept and warn on the deprecated tok_lang argument to make_g2p.

While I'm there, clean up other compatibility validation code.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.77%. Comparing base (b01734f) to head (fdacd74).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #362 +/- ## ========================================== + Coverage 93.59% 93.77% +0.17% ========================================== Files 17 16 -1 Lines 2341 2328 -13 Branches 520 517 -3 ========================================== - Hits 2191 2183 -8 + Misses 85 82 -3 + Partials 65 63 -2 ```

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[github-actions[bot]]

CLI load time: 0:00.05
PR head fdacd74afc889c9665e5dfafc30a2713fd3b3849
Imports that take more than 0.1 s:
import time: self [us] | cumulative | imported package