build(deps): bump r2-shared-js from 1.0.74 to 1.0.77

Bumps [r2-shared-js](https://github.com/readium/r2-shared-js) from 1.0.74 to 1.0.77.
- [Changelog](https://github.com/readium/r2-shared-js/blob/develop/CHANGELOG.md)
- [Commits](readium/r2-shared-js@v1.0.74...v1.0.77)

---
updated-dependencies:
- dependency-name: r2-shared-js
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>