build(deps): bump tree-kill from 1.2.1 to 1.2.2 in /examples/lb3-express (#21)

Bumps [tree-kill](https://github.com/pkrumins/node-tree-kill) from 1.2.1 to 1.2.2.
- [Release notes](https://github.com/pkrumins/node-tree-kill/releases)
- [Commits](pkrumins/node-tree-kill@v1.2.1...v1.2.2)

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