use the latest 0.1.x stable gradual flow plugin

conanfile.py

@@ -311,7 +311,7 @@ class CuraConan(ConanFile):
         self.requires("curaengine/(latest)@ultimaker/testing")
         self.requires("pysavitar/5.3.0")
         self.requires("pynest2d/5.3.0")
-        self.requires("curaengine_plugin_gradual_flow/(latest)@ultimaker/testing")
+        self.requires("curaengine_plugin_gradual_flow/(latest)@ultimaker/stable")
         self.requires("uranium/(latest)@ultimaker/testing")
         self.requires("cura_binary_data/(latest)@ultimaker/testing")
         self.requires("cpython/3.10.4")