Read MIN_GO_VERSION directly with Go CLI

[y1hao]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

In hack/util.sh, we can directly read MIN_GO_VERSION from go.mod via Go CLI. No need to remember to modify it manually when updating Go version.

Discussed here: #6066 (comment)

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.35%. Comparing base (d24b2b9) to head (0d9dd14).

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Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6085   +/-   ##
=======================================
  Coverage   48.35%   48.35%           
=======================================
  Files         666      666           
  Lines       54880    54880           
=======================================
  Hits        26537    26537           
+ Misses      26618    26617    -1     
- Partials     1725     1726    +1     

Flag	Coverage Δ
unittests	48.35% <ø> (ø)

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[RainbowMango]

/lgtm
/approve
Thanks.

[karmada-bot]

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This pull-request has been approved by: RainbowMango

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