ci: remove pinned npm version once npm/cli#9151 is resolved

## Context

In #2299, we pinned npm to version 11.11.0 in `.github/actions/dependencies/action.yml` as a workaround for https://github.com/npm/cli/issues/9151. This was needed because `npm install -g npm@11` fails with a `MODULE_NOT_FOUND` error for `promise-retry` when running on Node 22 with `setup-node` v6.

## Task

Once https://github.com/npm/cli/issues/9151 is resolved and a fixed version of npm is available:

1. Remove the pinned npm version (`11.11.0`) from `.github/actions/dependencies/action.yml`
2. Update the install step back to `npm install -g npm@11` (or whichever major version is current)
3. Verify CI workflows pass without the workaround