v0.4.2

What's Changed

• Update dependency @types/jest to v23.3.1 (#15) @renovate[bot]
• Update dependency jest to v23.4.2 (#16) @renovate[bot]
• Update dependency rollup to v0.63.5 (#19) @renovate[bot]
• Update dependency typescript to v3 (#18) @renovate[bot]
• Add bundlephobia badge (#20) @abraham