PMM-15099 Bump Go version to 1.26.5

[ademidoff]

Ticket number: PMM-15099

This pull request updates the Go version used in the go.mod file from 1.26.4 to 1.26.5. This is a minor version bump, to include the latest bug fixes and improvements.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.09%. Comparing base (31318c7) to head (8bfcbfb).
⚠️ Report is 25 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5638      +/-   ##
==========================================
+ Coverage   43.59%   44.09%   +0.49%     
==========================================
  Files         415      416       +1     
  Lines       43134    43067      -67     
==========================================
+ Hits        18804    18989     +185     
+ Misses      22454    22200     -254     
- Partials     1876     1878       +2     

Flag	Coverage Δ
admin	34.78% <ø> (ø)
agent	50.16% <ø> (+1.11%)	⬆️
managed	43.29% <ø> (+0.30%)	⬆️
vmproxy	72.22% <ø> (ø)

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