*: bump go v1.26

[KaloyanTanev]

Bump go to v1.26 and fix linting

category: misc
ticket: none

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.43%. Comparing base (42a1c2d) to head (42fc194).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
core/validatorapi/router.go	0.00%	5 Missing ⚠️
cmd/enr.go	0.00%	2 Missing ⚠️
cmd/createcluster.go	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4328      +/-   ##
==========================================
+ Coverage   56.40%   56.43%   +0.02%     
==========================================
  Files         237      237              
  Lines       31697    31697              
==========================================
+ Hits        17880    17887       +7     
+ Misses      11529    11519      -10     
- Partials     2288     2291       +3     

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