[12.x] chore: add deprecation to Request::get()

[calebdw]

The parent method is deprecated, but it doesn't show up in the IDE because the child method is not marked as deprecated.

Thanks!

[calebdw]

@taylorotwell, can we please get a patch release so I don't have to wait a week for the warnings to go away? 🙏

[m0nclous]

Hi @taylorotwell,
I saw that my PR (#58617) with a similar change was rejected.
I would really appreciate any feedback on what was incorrect in my implementation or how it could be improved. This would help me contribute more effectively in the future.

[calebdw]

@m0nclous, I can't speak for Taylor, but here's some things I've noticed:

• sometimes he'll merge a PR if it's suggested multiple times by different people
• sometimes it depends on the particular implementation, if it's clean or minimal perhaps
• Taylor cares about IDE help, which I brought up in the description