This PR adds new granular tokens per minute columns to the `models`
table in preparation for more fine-grained rate limits.
The following columns have been added:
- `max_input_tokens_per_minute`
- `max_output_tokens_per_minute`
These mirror the "Maximum input tokens per minute (ITPM)" and "Maximum
output tokens per minute (OTPM)" [rate limits from
Anthropic](https://docs.anthropic.com/en/api/rate-limits#rate-limits).
Release Notes:
- N/A
cf0d1e4229