fix: support for custom key map

[xesina]

With a custom key map, we get a panic.

package main

import "github.com/go-faker/faker/v4"

func main()  {
	type CustomString string
	type CustomStruct struct {
		Map map[CustomString]string
	}

	faker.FakeData(&CustomStruct{})
}

This PR will fix this issue by converting the reflected map key.

[codecov-commenter]

Codecov Report

Base: 88.99% // Head: 88.99% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (eb8370e) compared to base (12df95a).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #16   +/-   ##
=======================================
  Coverage   88.99%   88.99%           
=======================================
  Files          12       12           
  Lines        1735     1736    +1     
=======================================
+ Hits         1544     1545    +1     
  Misses        137      137           
  Partials       54       54           

Impacted Files	Coverage Δ
faker.go	85.87% <100.00%> (+0.01%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.