Update update-next.yml

[mstrasinskis]

Motivation

Stop installing the latest npm. Because it's not compatible with the current node version.

Changes

• Commend out install latest npm.

Tests

• Pass

Todos

• Add entry to changelog (if necessary).
  Not necessary

[yhabib]

Adding a bit of context:

• Our current update actions for the npm packages gix and ic-js are broken. This issue stems from a line that attempts to install the latest version of npm, as seen here: https://github.com/dfinity/nns-dapp/actions/runs/12411288061/job/34648665259#step:5:15.
• The problem arose because npm@11 was released three days ago: https://github.com/npm/cli/releases/tag/v11.0.0. They state that they do not support node@18, which disrupts our current workflow.
• We have also identified that both gix and ic-js do not specify the node version. Currently, we rely on GitHub runners and the Ubuntu version, but this approach is somewhat unreliable. We should investigate this in a separate branch.

[dskloetd]

Tests

• Pass

What does this mean? How is this tested?