update fsevents and chokidar

[m-shaka]

Hi. When using elm-test with node v10, this error occurs.

To fix this, I updated some dependencies.

[rtfeldman]

@m-shaka Can you rebase on current master and pin the dependencies to exact versions? (no ^ in them, that is.)

Thanks for this!

[halfzebra]

@m-shaka good stuff! 👍

@rtfeldman what do you think of removing package-lock.json and setting fsevents and chokidar versions to "latest minor version"? I do not suggest that this is applicable to all the packages, but those two are fairly reliable in terms of semver.

[rtfeldman]

Thanks @m-shaka!

@halfzebra for applications I always like to pin dependencies exactly, so if two teammates install the same version they're always getting the same thing. Cuts down on "I can't reproduce; maybe uninstall and reinstall?"