Delete GitHub workflows

[freearhey]

Changes:

• deleted the .github/workflows directory
• deleted scripts db:clear, db:matrix, db:update and cluster:load
• added new NPM scripts:
  • check: checks all files in the /streams for syntax errors and compares channel IDs with those in iptv-org/database
  • update: generates all playlists, creates streams.json and updates README.md
  • deploy: publishes generated playlists and streams.json to GitHub Pages
• since automatic link checking is no longer possible, stream status, resolution and frame rate will no longer be taken into account when generating playlists
• for the same reason the fields status, width, height, bitrate, frame_rate, added_at, updated_at and checked_at removed from streams.json
• also removed the mention of EPG from the repository at least until issue Set up new build/CI system iptv-org.github.io#425 is resolved