Get rid of izulu

[mahenzon]

idk why we need izulu here. It's a strange lib.

What concerns me:

• why we froze version 0.50.0 when there's already 0.75.0?
• why all latest releases of izulu are broken?
• why rely on a 3rd-party library that has exactly one maintainer?
• why izulu claims that it's MIT-licensed, but in the license file it has custom license?

taskiq doesn't even utilize so much from the izulu library.

Let's get rid of it. It's just about 70 lines of code.

Here's my MIT-licensed source code that can be just copy-pasted into the project. Remember the left-pad.

https://gist.github.com/mahenzon/5ac32267ebd6d29a44dd52bb94a9630c

[codecov]

Codecov Report

❌ Patch coverage is 98.07692% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79.00%. Comparing base (dade604) to head (a37563c).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
taskiq/error.py	98.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #606      +/-   ##
==========================================
+ Coverage   78.45%   79.00%   +0.55%     
==========================================
  Files          68       69       +1     
  Lines        2413     2463      +50     
==========================================
+ Hits         1893     1946      +53     
+ Misses        520      517       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.