Merge Dev to Main

[vb2007]

New commands:

• /say - https://github.com/vb2007/discordbot/issues/15
• /911-countdown - https://github.com/vb2007/discordbot/issues/63
• /rename - https://github.com/vb2007/discordbot/issues/14
• /beg - https://github.com/vb2007/discordbot/issues/57

Other changes:

• Added unit test for checking if all commands in the filesystem really are in the /help command: https://github.com/vb2007/discordbot/issues/73
• Updated GitHub actions file for running test
• Fixed bugs / added feature to /leaderboard: https://github.com/vb2007/discordbot/issues/69 , https://github.com/vb2007/discordbot/issues/70
• Fixed bug with /balance: https://github.com/vb2007/discordbot/issues/35
• Made the bot run as a systemd service in the background on Linux servers + added documentation for it: https://github.com/vb2007/discordbot/issues/49
• Added test check badge to README.md
• Made /leaderboard and the whole economy system work correctly across servers
• Other minor changes