Misleading message “This PR introduced no changes to the JavaScript bundle”

The message “This PR introduced no changes to the JavaScript bundle” is misleading. It implies that the resulting JavaScript bundles are exactly the same bytes (not just the same lengths!), so if the PR intended to make some end-user-visible change, it is failing to do so. This can cause people (in particular people not familiar with the `nextjs-bundle-analysis` action) to think their changes are having no effect on end-user code, and waste time troubleshooting that.

The intended meaning is of course something like “This PR did not change any JavaScript bundle sizes [beyond the configured threshold]”.