Petlja-api

**Full Changelog**: https://github.com/PavleSekesan/petlja_api/compare/v0.2.0...v0.3.0

**Full Changelog**: https://github.com/PavleSekesan/petlja_api/compare/v0.1.1...v0.2.0

make required python version >=3.8 and fix compatibility issues with 3.8

Added functions:
- submit_solution_detailed - returns time, memory, and status for each testcase
- set_time_limit, set_memory_limit - sets time and memory limits for a problem
- delete_problem, delete_competition