fix wrong enum on SubjectAltNameType

[zirain]

Valid values for SubjectAltNameType as following:

// SubjectAltNameType is the type of the Subject Alternative Name.
// +kubebuilder:validation:Enum=Hostname;URI
type SubjectAltNameType string

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.60%. Comparing base (e0e8a29) to head (1b713fd).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6307      +/-   ##
==========================================
- Coverage   70.60%   70.60%   -0.01%     
==========================================
  Files         220      220              
  Lines       36829    36829              
==========================================
- Hits        26004    26003       -1     
  Misses       9292     9292              
- Partials     1533     1534       +1     

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[zirain]

@arkodg need cherry-pick? at least for v1.4?

[arkodg]

yeah we need to, will add the label to it, thanks @zirain