FIx string generation and remove non alphanumeric character

Author: nodauf

src/utils/utils.go

@@ -34,7 +34,7 @@ func GetStringOrFile(arg string) string {
 
 // RandomString return a string of length n
 func RandomString(n int) string {
-	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_")
+	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
 
 	s := make([]rune, n)
 	for i := range s {