fix/ci: install instructions, build with latest js-pdk

[G4Vi]

Having the dependencies section in the yaml, when a dependency is missing, prevents the prepare script from running and displaying a more helpful error message.

[nilslice]

Is there potentially another layer this could be fixed at, like in the CLI so that it doesn't entirely exit, or maybe checks these dependencies listed after the prepare script?

The way I read this PR is that we now won't report the deps missing as part of our diagnosis. Could be misreading though!

[G4Vi]

We could change the cli to check the deps section after. However, it would be redundant as the prepare script checks and reports if they are missing. In https://github.com/dylibso/xtp/pull/994#discussion_r1927155042 @bhelx mentioned that the dependencies section was deprecated in favor of the prepare script and I see the dependencies section was removed from the typescript bindgen.

When extism-py is missing, with this PR the output looks like:

gavin@Gavins-MacBook-Pro cli % go run app/main.go plugin init --template ../../xtp-python-bindgen/bundle --name theplugin --path theplugin
Generating plugin for Tool in theplugin...
👉 Running prepare script: bash prepare.sh && uv sync
❌ extism-py is not installed.

extism-py is needed to compile the plug-in. You can find the instructions to install it here: https://github.com/extism/python-pdk

Alternatively, you can use an install script.

🔹 Mac / Linux:
curl -L https://raw.githubusercontent.com/extism/python-pdk/main/install.sh | bash

Error: error generating plugin: failed to run prepare script: exit status 1
Log file: /Users/gavin/Library/Caches/xtp/xtp-1737656400-18818.log
exit status 1