Add support for PaLM

[rmitsch]

Description

Add support for PaLM.

Corresponding documentation PR

explosion/spaCy#13018

Types of change

New feature.

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran all tests in tests and usage_examples/tests, and all new and existing tests passed. This includes
  • all external tests (i. e. pytest ran with --external)
  • all tests requiring a GPU (i. e. pytest ran with --gpu)
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[beornf]

I tested using PaLM and noticed the model directory palm has not been imported here:

spacy-llm/spacy_llm/models/rest/__init__.py

Lines 1 to 9 in fad5253

	from . import anthropic, base, cohere, noop, openai
	__all__ = [
	"anthropic",
	"base",
	"cohere",
	"openai",
	"noop",
	]

[rmitsch]

Thanks for the heads-up! Will be fixed later today.