Fix JSON unmarshalling issue in Validate method.

Replaced hardcoded string concatenation with fmt.Sprintf for better readability and maintainability. This change ensures that the JSON string is correctly formatted before unmarshalling.

uzi_vc_validator/ura_validator.go

@@ -34,7 +34,7 @@ type JwtHeaderValues struct {
 
 func (u UraValidatorImpl) Validate(jwtString string) error {
 	credential := &vc.VerifiableCredential{}
-	err := json.Unmarshal([]byte("\""+jwtString+"\""), credential)
+	err := json.Unmarshal([]byte(fmt.Sprintf("\"%s\"", jwtString)), credential)
 	if err != nil {
 		return err
 	}