Upgrade babel/preset-env to ^7.9.0 for Node 13+ compatibility

[dabrady]

The current LTS version of Node.js is 14.x.

However, attempting to compile and run the local dev server for this project using v16.0.0 (the latest active version of Node) fails to build with this error:

Error: Cannot find module '@babel/compat-data/corejs3-shipped-proposals'
Require stack:
- /tmp/[eval]
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:952:15)
    at Function.resolve (internal/modules/cjs/helpers.js:78:19)
    at [eval]:1:9
    at Script.runInThisContext (vm.js:131:20)
    at Object.runInThisContext (vm.js:297:38)
    at Object.<anonymous> ([eval]-wrapper:10:26)
    at Module._compile (internal/modules/cjs/loader.js:1123:30)
    at evalScript (internal/process/execution.js:94:25)
    at internal/main/eval_string.js:23:3 {
  code: 'MODULE_NOT_FOUND',
  requireStack: [ '/tmp/[eval]' ]
}

This is the same error reported as an issue here on the Node project, and the solution recommended is to upgrade the project's version of @babel/preset-env to at least v7.9.0. That is what I have done here, and it resolves the build error on my machine when compiling with v16.0.0.

Of course, if we don't actually want to be running this project using Node.js 13.13+, this is unnecessary. As a new contribooter, I do not have context around our stance there. Any feedback is welcome here 🙇🏻

[dabrady]

I've forgotten about this, and I'm not going to prioritize it if it's not causing issues right now. Closing.