package-lock.json: update to lockfileVersion 2

Update by running: npm i --package-lock-only

According to
https://docs.npmjs.com/cli/v8/configuring-npm/package-lock-json#lockfileversion
lockfileVersion 2 is backwards compatible with 1 but adds extra metadata
to aid with performance and reproducible builds.

Additionally, swagger-ui already uses lockfileVersion 2 in its
package-lock.json.