* Use `packageManager` field to define pnpm version in one place
* Update to pnpm 8.1.0 (see also #17990)
* Enforce pnpm >= 8 via `engines`
* Clean-up `engines` & remove `volta`
* Add dedup workaround, consolidate test env prepare steps
* No checkout, no action :-)
* Bump minimal pnpm version to 8.1.0
Co-authored-by: Rijk van Zanten <rijkvanzanten@me.com>
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Co-authored-by: Rijk van Zanten <rijkvanzanten@me.com>