Fix prepare script, consumers should not need to have yarn to be able to install package as a git dependency in package.json

[scmx]

Currently when installing the package it will crash if yarn isn't installed. Because the prepare script runs on consumers machines after install.

Suggested solution: Run tsc directly instead.

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Thanks for this nice package by the way! 🎉

[scmx]

Had a hard time reproducing this myself. But apparently we had this in package json when the problem occurred (leftover since some earlier point when a problem was fixed in main but not yet published).
"@trivago/prettier-plugin-sort-imports": "github:trivago/prettier-plugin-sort-imports",
and got:
npm ERR! sh: yarn: command not found
Changing to direct npm version solves it. Or installing yarn.
With docker node image yarn is available so no problem there.
🤷