chore: parse escaped double colon (\\:) example struct tag (#1402)

* chore: parse escaped double colon (\\:) example struct tag

Replaces the regular string splitting by a ":" made during
the "example" tag parsing so that it will not split escaped
double colons, allowing string examples containing a double
colon to be escaped using double backlashes.

* refactor: use strings.SplitN to split the string by the first double colon found

Co-authored-by: Gustavo <gustavo.antoniassi@ifood.com.br>

parser.go

@@ -1441,7 +1441,7 @@ func defineTypeOfExample(schemaType, arrayType, exampleValue string) (interface{
 		result := map[string]interface{}{}
 
 		for _, value := range values {
-			mapData := strings.Split(value, ":")
+			mapData := strings.SplitN(value, ":", 2)
 
 			if len(mapData) == 2 {
 				v, err := defineTypeOfExample(arrayType, "", mapData[1])