db manager: fix setting of contrast enhancement for spatialite rasters (fixes #12497)

Author: jef-n

python/plugins/db_manager/db_plugins/spatialite/plugin.py

@@ -230,11 +230,11 @@ def mimeUri(self):
         return uri
 
     def toMapLayer(self):
-        from qgis.core import QgsRasterLayer
+        from qgis.core import QgsRasterLayer, QgsContrastEnhancement
 
         rl = QgsRasterLayer(self.gdalUri(), self.name)
         if rl.isValid():
-            rl.setContrastEnhancementAlgorithm("StretchToMinimumMaximum")
+            rl.setContrastEnhancement(QgsContrastEnhancement.StretchToMinimumMaximum)
         return rl