Updates needed for post-2021

[brodycj]

updated

• [ ] highly recommended: rename default branch to main, which would (possibly) affect the branch name for adding GitHub CI workflows
• [ ] add LICENSE file to npm package - done in PR #59
• [ ] test Babel build output - done in PR #59
• [ ] use something like jest-matcher-deep-close-to to avoid minor Webpack size variations between Linux, Windows, macOS (etc.) - done in PR #59 ... ref:
  • https://github.com/facebook/jest/issues/4058#issuecomment-316138505
  • https://github.com/facebook/jest/issues/3654
• [ ] switch from Travis CI to GitHub workflows - done in PR #59
• [ ] highly recommended: make Webpack optional as I suggested in https://github.com/TrySound/rollup-plugin-size-snapshot/issues/47#issuecomment-985086426
• [ ] update for recent Webpack v5 release to avoid an issue with Node.js 17 - done in PR #59 ... ref:
  • https://github.com/react-recompose/react-recompose/issues/13
  • https://github.com/webpack/webpack/issues/14532#issuecomment-985083189
  • https://github.com/microsoft/vscode-js-debug/pull/1146
• [ ] update more dependencies
• [ ] address some other issues

I have already got Webpack v5 working in my work area ... and working with Node.js 17, would be happy to work on the other items (except for renaming the default branch) if anyone is interested.