Allow specifying colors

[petermarathas]

What this PR does / Why we need it

Enhancement for specifying colors via new colors input. If the label returned from github does not match what's in the input, an update call is made. Errors in the update request won't fail the action.

Which issue(s) this PR fixes

Fixes #479

Example file and screenshots:

on: issue_comment

jobs:
  all_tests:
    name: All Tests
    runs-on: ubuntu-latest
    steps:
      - name: My first step - check out repository
        uses: actions/checkout@v4
      - name: No Color
        uses: ./
        with:
          labels: No Color
      - name: One Color One Label
        uses: ./
        with:
          labels: One Color One Label
          colors: ff0000
      - uses: ./
        name: One Color Many Labels
        with:
          labels: |
            One Color Many Labels 1
            One Color Many Labels 2
          colors: ffff00
      - uses: ./
        name: Many Colors Many Labels
        with:
          labels: |
            Many Colors Many Labels 1
            Many Colors Many Labels 2
          colors: |
            00ff00
            0000ff
      - uses: ./
        name: More Colors Than Labels
        with:
          labels: More Colors Than Labels
          colors: |
            00ffff
            0000ff
      - uses: ./
        name: Adding Color Has Errors
        with:
          labels: |
            Adding Color Has Errors 1
            Adding Color Has Errors 2
          colors: |
            zzz
            ff000f