Support pnpm 9

[CraigMacomber]

Support pnpm lock file format 9.0 used by pnpm 9.

Pnpm 8 is supported until April 2025, so for pnpm to remain supported, support for pnpm 9 should land enough before that to allow users to migrate.

[CraigMacomber]

pnpm has provided a 379 day window to migrate from pnpm 8 to pnpm 9 before security patches will no longer be provided. Over 25% of this time has now passed. I'm glad to see work on this is considered "ready" and I hope it gets implemented soon.

[CraigMacomber]

About 40% of the time-window for migrating from pnpm 8 to 9 has passed. "Status" has not changed since my last post.

pnpm 9 has had 23 stable releases: even though pnpm 8 is still getting security patching, it would be great to be able to move onto pnpm 9 and take advantage of all that new development work.

Is there any estimate of when pnpm 9 support will land?