Flow test improvements

[GuyAv46]

Main objects this PR modified

1. Change a class name to follow the pytest syntax
2. Bump pytest version to solve deprecation warnings

Mark if applicable

• This PR introduces API changes
• This PR introduces serialization changes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.09%. Comparing base (63badf2) to head (d44caa3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #585   +/-   ##
=======================================
  Coverage   97.09%   97.09%           
=======================================
  Files         104      104           
  Lines        5503     5503           
=======================================
  Hits         5343     5343           
  Misses        160      160           

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[github-actions]

Backport failed for 0.7, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 0.7
git worktree add -d .worktree/backport-585-to-0.7 origin/0.7
cd .worktree/backport-585-to-0.7
git switch --create backport-585-to-0.7
git cherry-pick -x bcb303304d016530a87f43351e0de8f145150fbe

[github-actions]

Successfully created backport PR for 0.8:

• [0.8] Flow test improvements #586

[github-actions]

Successfully created backport PR for 8.0:

• [8.0] Flow test improvements #587