Bump @blockly/block-test from 1.0.12 to 1.0.13 (#4800)

Bumps [@blockly/block-test](https://github.com/google/blockly-samples/tree/HEAD/plugins/block-test) from 1.0.12 to 1.0.13.
- [Release notes](https://github.com/google/blockly-samples/releases)
- [Commits](https://github.com/google/blockly-samples/commits/@blockly/block-test@1.0.13/plugins/block-test)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>