TG-235 Fix cursor.warnings field type (#389)

Author: jwierzbo

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [master](https://github.com/arangodb/go-driver/tree/master) (N/A)
 - Add support for `exclusive` field for transaction options
 - Fix cursor executionTime statistics getter
+- Fix cursor warnings field type
 
 ## [1.3.0](https://github.com/arangodb/go-driver/tree/v1.3.0) (2022-03-17)
 - Disallow unknown fields feature

cursor_impl.go

@@ -92,7 +92,12 @@ type cursorExtra struct {
 	Stats    cursorStats   `json:"stats,omitempty"`
 	Profile  cursorProfile `json:"profile,omitempty"`
 	Plan     *cursorPlan   `json:"plan,omitempty"`
-	Warnings []string      `json:"warnings,omitempty"`
+	Warnings []warn        `json:"warnings,omitempty"`
+}
+
+type warn struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
 }
 
 func (c cursorExtra) GetStatistics() QueryStatistics {