fix: allow leading space in i18n description comments

[Nodge]

lingui extract ignores messages with leading space in description comment.

Example source code:

/* i18n: description */t`Message`

Expected messages:

{
  "Message": {
    "translation": "Message",
    "description": "description",
    "origin": [
      [
        "test.js",
        1
      ]
    ]
  }
}

Actual messages:

{}

[tricoder42]

Released in v2.7.1