Fix CVE-2020-7774

[vecerek]

The PR fixes https://nvd.nist.gov/vuln/detail/CVE-2020-7774.

References

[vecerek]

@darcyclarke tests in some environments are failing and I cannot reproduce them locally. Instead of the 6 failing tests I get:

3926 passing (5m)
  11 pending
  1 failing

The failing test being:

not ok should match pattern provided
    found: ''
    pattern: /Check if the file 'emacsclient' is present./
    at:
      line: 26
      column: 7
      file: test/tap/spawn-enoent-help.js
      type: global
    stack: |
      test/tap/spawn-enoent-help.js:26:7
      f (node_modules/once/once.js:25:25)
      ChildProcess.<anonymous> (test/common-tap.js:175:5)
    source: |
      t.similar(serr, /Check if the file 'emacsclient' is present./)

I believe I need help addressing the failing tests 🙁

[darcyclarke]

@vecerek apologize for the delayed response here; I went digging to try & figure out why this CVE isn't in GitHub/npm's Advisory DB - I'm hoping we can figure that out but will also cut a v6 release addressing this prod-dep patch as soon as I can.