Finalize fix for npm release flow

[turt2live]

Fixes #58

Requires trusted publishing to be enabled on the NPM side.

Instructions post-merge to finish the outstanding release:

1. Delete any draft releases.
2. Go here and click "Run workflow" in the blue banner talking about workflow_dispatch triggers.
3. Keep the branch as main
4. Set the tag to v0.4.0
5. Click "Run workflow"
6. Wait ~15 minutes for the build
7. Verify success (may require a page refresh to show the job)

[turt2live]

Release published: https://www.npmjs.com/package/@matrix-org/matrix-sdk-crypto-nodejs/v/0.4.0