Rate limiter

[9helix]

Description

Added rate limiter for the API using the Upstash rate limit.
Upstash account and Redis database created on it needed. More info: https://upstash.com/docs/redis/overall/getstarted
Credentials need to be provided in .env like this:
UPSTASH_REDIS_REST_URL="[database link]"
UPSTASH_REDIS_REST_TOKEN="[database token]"

Change summary

• Initialized limiter
• Set up error throwing when limit is exceeded

Checklist

• I have performed a self-review of my code
• I tested locally
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New package or package update introduced

[9helix]

Now I've added the ability to enable the limiter (disabled by default) from the .env file using the variable RATE_LIMITER_ENABLED. Set it to either true or false.

[IMilja]

Looking good to me. I requested two small changes and after you implement them we can merge the changes :)