chore: Update workflow and tools to use Go 1.26 and 1.25

[gmlewis]

cc: @stevehipwell - @alexandear - @zyfy29 - @Not-Dhananjay-Mishra

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.52%. Comparing base (1732098) to head (1c05738).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3995   +/-   ##
=======================================
  Coverage   93.52%   93.52%           
=======================================
  Files         207      207           
  Lines       17591    17597    +6     
=======================================
+ Hits        16452    16458    +6     
  Misses        938      938           
  Partials      201      201           

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[Not-Dhananjay-Mishra]

LGTM.
Just one question should we update README.md as well?

go-github/README.md

Lines 15 to 16 in 1732098

	We do our best not to break older versions of Go if we don't have to, but we
	don't explicitly test older versions and as of Go 1.23 the go directive in

[gmlewis]

LGTM. Just one question should we update README.md as well?

go-github/README.md

Lines 15 to 16 in 1732098

	We do our best not to break older versions of Go if we don't have to, but we
	don't explicitly test older versions and as of Go 1.23 the go directive in

No, that section should stay the same.

[alexandear]

Could we ship this change after the go-github release with all the breaking changes? I mean releasing v83 first and then updating the go.mod to Go 1.25.

[gmlewis]

Could we ship this change after the go-github release with all the breaking changes? I mean releasing v83 first and then updating the go.mod to Go 1.25.

Great idea, @alexandear - placing this PR on hold until after the release of v83.0.0.