feat: add trusted issuers for request token verification

[alexhook]

PR checklist

• I've written good commit message for all commits
• I've split changes into separate commits where it's appropriate
• I've added the description of function to documentation
• I've updated project version in pyproject.toml
• I'll make a release when PR is merged
• I'll bump pybotx in bot-template

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (dc7da94) to head (a07f565).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #488   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          121       121           
  Lines         4242      4244    +2     
  Branches       365       366    +1     
=========================================
+ Hits          4242      4244    +2     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

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