ci: use separate modfile for Go tools

[michaeladler]

Description

A separate modfile is now used for managing Go tools, preventing potential version conflicts stemming from transitive dependencies. This change simplifies dependency management and clarifies which dependencies are included in the final binaries.

Issues Addressed

List and link all the issues addressed by this PR.

Change Type

Please select the relevant options:

• Bug fix (non-breaking change that resolves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• I have read the CONTRIBUTING document.
• My changes adhere to the established code style, patterns, and best practices.
• I have added tests that demonstrate the effectiveness of my changes.
• I have updated the documentation accordingly (if applicable).
• I have added an entry in the CHANGELOG to document my changes (if applicable).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.82%. Comparing base (f0a183f) to head (c8a2ceb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #382   +/-   ##
=======================================
  Coverage   81.82%   81.82%           
=======================================
  Files          93       93           
  Lines        3845     3845           
=======================================
  Hits         3146     3146           
  Misses        450      450           
  Partials      249      249           

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