Typo in the Rhino beetle prompt (from the paper)

There is (as far as my knowledge of English goes) a typo in this prompt, which also features in the paper and in the [project homepage](https://parti.research.google/):

https://github.com/google-research/parti/blob/9c7c579a38995beeab4a6f613098ff8f8f6a959c/PartiPrompts.tsv#L720

it should read:

```diff
- A rhino beetle this size of a tank grapples a real life passenger airplane on the tarmac
+ A rhino beetle the size of a tank grapples a real life passenger airplane on the tarmac
```

I don't believe it's intentional, since [the paper](https://gweb-research-parti.web.app/parti_paper.pdf) doesn't mention augmentations of the dataset to account for common spelling mistakes, and seems to assume that the prompts are formally correct.

Start with PartiPrompts.tsv at line 720 and compare the Rhino beetle prompt with the linked paper and project homepage. Correct the wording in each referenced location, then verify that the prompt consistently uses “the size of a tank” and that no unintended wording changes were introduced.

Written by the indexing model from the issue text.