chore(deps): update go toolchain directive to 1.26.4

[renovate-vince-riv]

This PR contains the following updates:

Package	Type	Update	Change
go (source)	toolchain	minor	1.25.6 → 1.26.4

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.50%. Comparing base (a8ccb8d) to head (561a9ff).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #55   +/-   ##
=======================================
  Coverage   88.50%   88.50%           
=======================================
  Files          10       10           
  Lines         400      400           
=======================================
  Hits          354      354           
  Misses         36       36           
  Partials       10       10           

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