feat: Add route blocking and caching

[FoxxMD]

• Implement blocking non-robots routes based on ai.robots.txt
  • Add test for blocking
• Add caching for ai.robots.txt Add a cache to reduce the number of calls to raw.githubusercontent.com #8

[FoxxMD]

I have not had much experience with Go so I'm sure my code is sloppy and not using best practices. Please feel free to suggest changes or make them yourself.

These changes implement caching for ai.robots.txt and an optional behavior to block non robots.txt routes based on the User-Agent identifiers found in ai.robots.txt (also cached).

Most of the code for blocking is pulled from https://github.com/edelbluth/tm_no_ai_bots

[FoxxMD]

All of the functionality works when using local mode on my prod traefik instance BUT making a change to any of the options for the middleware seems to cause an error when traefik reloads config...