`lerna` is a bit stale, and as such it currently has some outdated
dependencies which Dependabot warns on.
Fortunately, npm 7 supports monorepos natively, via "workspaces". So
simply replace `lerna` with this feature. The migration is pretty
neat and requires a very little invervention.
Because Node.js 14 comes with npm 6 by default, upgrade it manually
as shown in https://github.com/bahmutov/npm-install/issues/103#issuecomment-931226602.
As usual, also bump its helper crates (`js-sys`, `wasm-bindgen-futures`)
to the latest versions, except for `web-sys` which is locked by wgpu
to 0.3.50.
The previous approach of `paths-ignore` was flawed because currently
it doesn't interact well with GitHub's "Require status checks to pass
before merging" setting. As a result, PRs that didn't trigger all
workflows couldn't be merged, because GitHub waited for the skipped
workflows to finish.
`dorny/paths-filter` is a somewhat elegant workaround proposed in
https://stackoverflow.com/questions/66751567.
* dev: run workflows only if certain file paths change
* fix: looks like you can't ? a /
* feat: simpler approach
Don't run Rust if only package.json, package-lock.json or anything under
web/packages has changed.
Don't run either if they only have docs changes.
Also bump its helper crates (js-sys, wasm-bindgen-futures) to the
latest versions, except for web-sys which seems to be locked by wgpu
to one version before the latest (0.3.50).
relrelb