chore(deps): update go toolchain directive to v1.26.3

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
go (source)	toolchain	patch	1.26.2 → 1.26.3

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Release Notes

golang/go (go)

v1.26.3

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.18%. Comparing base (99b02d6) to head (9972fbf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2903      +/-   ##
==========================================
- Coverage   86.18%   86.18%   -0.01%     
==========================================
  Files         714      714              
  Lines      270516   270516              
==========================================
- Hits       233135   233131       -4     
- Misses      36857    36861       +4     
  Partials      524      524              

Components	Coverage Δ
otap-dataflow	87.13% <ø> (-0.01%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.73% <ø> (ø)
otel-arrow-go	52.45% <ø> (ø)
quiver	92.25% <ø> (ø)

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