Implement an "install -U" option for Updating llm

[knbknb]

In your blog post "Gemini 2.0 Flash: An outstanding multi-modal LLM with a sci-fi streaming mode" you give instructions

You’ ll need a Gemini API key—then install LLM and run:

llm install -U llm-gemini
Usage: llm prompt [OPTIONS] [PROMPT]
Try 'llm prompt --help' for help.

Error: No such option: -U

llm, version 0.19.1

But for me there is no "llm install -U" command. (I think one must uninstall and the install again)

I suggest to either implement it or fix the blog post.