fix(mqtt_cxx): Add explicit dependency on esp-mqtt if needed

Author: david-cermak

components/esp_mqtt_cxx/idf_component.yml

@@ -9,3 +9,7 @@ dependencies:
   # Required IDF version
   idf:
     version: ">=5.0"
+  espressif/mqtt:
+    rules:
+    - if: idf_version >=6.0
+      version: ^1.0.0