chore(deps): bump @blockly/workspace-backpack from 5.3.4 to 5.3.5

Bumps [@blockly/workspace-backpack](https://github.com/google/blockly-samples/tree/HEAD/plugins/backpack) from 5.3.4 to 5.3.5.
- [Release notes](https://github.com/google/blockly-samples/releases)
- [Commits](https://github.com/google/blockly-samples/commits/@blockly/[email protected]/plugins/backpack)

---
updated-dependencies:
- dependency-name: "@blockly/workspace-backpack"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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