Prepare v4.0.0 release (1st PS 0.15.0-compatible release) (purescript#30

)

* Update the bower dependencies

* Update Node to 14 in CI

* Update the changelog

Prepare v3.0.0 release (purescript#27)

Update CI to build with the latest version of the compiler, update the bower repository URL to match the URL in the registry, upgrade bower dependencies, and update the changelog.

Merge pull request purescript#4 from purescript/compiler/0.12

Update for PureScript 0.12

Merge pull request purescript#3 from i-am-tom/master

Add Monoid instance for Effect

Merge pull request purescript#2 from purescript/flatten-namespace

Flatten namespace to `Effect`

Update README badges