Update enzyme and remove enzyme-context-patch

[didoesdigital]

https://www.npmjs.com/package/enzyme-context-patch points to a merged PR
showing it is no longer needed. This fixes the build.

Before this fix, I was getting this error when I ran yarn install:

error /Users/di/projects/github/react-aria-live/node_modules/enzyme-context-patch: Command failed.
Exit code: 1
Command: echo 'Patching from postinstall.' && bin/patch-enzyme.sh
Arguments:
Directory: /Users/di/projects/github/react-aria-live/node_modules/enzyme-context-patch
Output:
Patching from postinstall.
Patching enzyme dependency for Context fix
patching file node_modules/enzyme-adapter-react-16/build/ReactSixteenAdapter.js
Hunk #1 FAILED at 56.
Hunk #2 FAILED at 114.
Hunk #3 FAILED at 145.
3 out of 3 hunks FAILED -- saving rejects to file node_modules/enzyme-adapter-react-16/build/ReactSixteenAdapter.js.rej
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.