Update tools/**/*.py, server/*.py and client/*.py files for PEP585 compliance.

[junkmd]

For the third step of #876.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.71%. Comparing base (4134455) to head (55eb586).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #879      +/-   ##
==========================================
+ Coverage   84.70%   84.71%   +0.01%     
==========================================
  Files         125      125              
  Lines       11536    11547      +11     
==========================================
+ Hits         9771     9782      +11     
  Misses       1765     1765              

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