Apos2.222.0 - Invalid RegEx path.sep missing "\"

Even though it isn't recommended to run ApostropheCMS on Windows, I've found a small bug which is worth opening a PR for.

## To Reproduce

Step by step instructions to reproduce the behavior:
1. Running ApostropheCMS 2 branch release-2.222.0 on Windows
2. `npm i` installs packages fine on Node 14,16 and 18
3. `npm start` is throwing an error with an invalid regular expression

## Expected behavior
Apostrophe should start as expected

## Describe the bug
Getting the following error when starting Apostrophe on a Windows environment:
```
kiichiro-toyoda-cms\node_modules\apostrophe\index.js:58
throw err;
^

SyntaxError: Invalid regular expression: /\node_modules\mocha\/: \ at end of pattern
at new RegExp ()
at getRoot (C:\Users\user\WebStormProjects\kiichiro-toyoda-cms\node_modules\apostrophe\index.js:259:35)
at module.exports (C:\Users\user\WebStormProjects\kiichiro-toyoda-cms\node_modules\apostrophe\index.js:35:33)
at Object. (C:\Users\user\WebStormProjects\kiichiro-toyoda-cms\app.js:334:35)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:14)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:76:12)
at internal/main/run_main_module.js:17:47
[nodemon] app crashed - waiting for file changes before starting...
```

A small update is required to a specific line within the root `index.js` file of the apostrophe release-2.222.0 branch, the following on line 259 should be updated from:
```
if (m.parent.filename.match(new RegExp(`${path.sep}node_modules${path.sep}mocha${path.sep}`))) {
```

to:
```
if (m.parent.filename.match(new RegExp(`${path.sep}node_modules${path.sep}mocha\${path.sep}`))) {
```

## Details
Windows uses

**Version of Node.js:**
Tested on Node 14, 16 and 18

**Server Operating System:**
Microsoft Windows

**Additional context:**
This is specific to Microsoft Windows, after forking at testing the above fix Apostrophe starts as expected including on both Linux and Mac.