🐛 utils.Trim wrong result if it should return a empty string

[trim21]

Fiber version

v2.26.0

Issue description

utils.Trim(" ", ' ') got " " instead of ""

Code snippet

package main_test

import (
	"strings"
	"testing"

	"github.com/gofiber/fiber/v2/utils"
	"github.com/stretchr/testify/assert"
)

func TestShouldBeEmptyString(t *testing.T) {
	assert.Equal(t, "", utils.Trim(" ", ' ')) // this is wrong, result is " "
	assert.Equal(t, "", strings.Trim(" ", " ")) // this is right
}

fix:

// Trim is the equivalent of strings.Trim
func Trim(s string, cutset byte) string {
	i, j := 0, len(s)-1
	for ; i < j; i++ {
		if s[i] != cutset {
			break
		}
	}
	for ; i < j; j-- {
		if s[j] != cutset {
			break
		}
	}

+	if i == j {
+		if s[i] == cutset {
+			return ""
+		}
+	}

	return s[i : j+1]
}