perf: improve variable declaration types and its order

[wellwelwel]

Just as the PR title says, this is a minimal improvement of variable declarations and their respective type and order.

• Also taking the occasion to update development dependencies.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (4005523) to head (5eda510).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #49   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines          196       197    +1     
=========================================
+ Hits           196       197    +1     

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