feat: voting outliers endpoint

[inimaz]

• GET /voting-outliers: Will return all the votes where there has been an outlier and the parlamentary group that has had it:
• Example:

[ 
...
  {
    "reference": "122/000034",
    "title": "Votación de conjunto ...",
    "group_votes": [
      {
        "name": "GMx",
        "votes": {
          "yes": 7,
          "no": 1,
          "abstention": 0,
          "skip": 0
        }
      }
    ]
  },
...
]

• query param exclude_group If we want to exclude a group (for instance Gmx since it has many sub-parties in it)

[pr3ssh]

👏 @inimaz, lo reviso en los próximos días.