Add "remote-branch" config parameter & handle scheme links failing with 404

[paul-ri]

• base16-universal-manager --update-list fails due to https://github.com/aramisgithub returning a 404 error
  • We're now printing an error message and moving on to the next color scheme
  • PR to remove links on source list at https://github.com/chriskempson/base16-schemes-source/pull/7
• Add remote-branch parameter to handle template repositories having a non master default branch. e.g. https://gitlab.com/ArenM/base16-foot is main
• Minor whitespace changes by the IDE

Testing done

• Add support for foot terminal using the new remote-branch parameter

  foot:
  enabled: true
  remote-branch: "main"
  files:
    default:
      path: ~/.config/foot/foot.ini
      mode: replace
      start_marker: "^# base16 start_marker$"
      end_marker: "^# base16 end_marker$"

• base16-universal-manager --update-list

  ❯ base16-universal-manager --update-list
  Found colorscheme repos:  77
  Getting schemes from: https://github.com/ajlende/base16-atlas-scheme
  [...]
  Getting schemes from: https://github.com/Misterio77/base16-sakura-scheme
  Getting schemes from: https://github.com/aramisgithub/base16-solarized-scheme
  Failed to get schemes from: https://github.com/aramisgithub/base16-solarized-scheme with error 'HTTP code 404'
  Getting schemes from: https://github.com/tartansandal/base16-dirtysea-scheme
  Getting schemes from: https://github.com/carloabelli/base16-equilibrium-scheme
  Getting schemes from: https://github.com/aramisgithub/base16-ia-scheme
  Failed to get schemes from: https://github.com/aramisgithub/base16-ia-scheme with error 'HTTP code 404'
  Getting schemes from: https://github.com/andreyvpng/base16-vulcan-scheme
  [...]