Updated dependencies to their latest version

[ijlee2]

Description

In this pull request, I updated dependencies that had released a major version. As I'm not too familiar with the packages, it's possible that I didn't address the breaking changes correctly.

Package                        Current Wanted  Latest Package Type    URL
@embroider/addon-dev           1.8.3   1.8.3   3.0.0  devDependencies https://github.com/embroider-build/embroider#readme
@embroider/test-setup          1.8.3   1.8.3   2.0.2  devDependencies https://github.com/embroider-build/embroider#readme
@rollup/plugin-babel           5.3.1   5.3.1   6.0.3  devDependencies https://github.com/rollup/plugins/tree/master/packages/babel#readme
release-it                     14.14.3 14.14.3 15.5.1 devDependencies https://github.com/release-it/release-it#readme
release-it-lerna-changelog     3.1.0   3.1.0   5.0.0  devDependencies https://github.com/rwjblue/release-it-lerna-changelog#readme
rollup                         2.79.1  2.79.1  3.7.5  devDependencies https://rollupjs.org/

For an up-to-date rollup configuration (e.g. need to change the file extension to .mjs), I referred to an addon generated by embroider-build/addon-blueprint.

References

See release notes for breaking changes:

• @embroider
• @rollup/plugin-babel
• release-it
• release-it-lerna-changelog
• rollup

[ijlee2]

I haven't tested the command yarn release-it. It's possible that I missed something when updating release-it and release-it-lerna-changelog.

[ijlee2]

I tested @embroider/* and rollup by running yarn start at the root directory. I was able to visit http://localhost:4200 and see the demo app render the <WelcomePage> component.

[ijlee2]

Forgot to remove this line in #388. (yarn sync-dev-deps is fallible.)

[ijlee2]

Forgot to remove this line in #388. (yarn sync-dev-deps is fallible.)