[processing] Fix negative distance value wrongly prohibited for multi…

… ring buffer (constant)

src/analysis/processing/qgsalgorithmmultiringconstantbuffer.cpp

@@ -71,7 +71,7 @@ void QgsMultiRingConstantBufferAlgorithm::initParameters( const QVariantMap & )
   addParameter( rings.release() );
 
   std::unique_ptr< QgsProcessingParameterDistance > distance = qgis::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "DISTANCE" ),
-      QObject::tr( "Distance between rings" ), 1, QStringLiteral( "INPUT" ), false, 0 );
+      QObject::tr( "Distance between rings" ), 1, QStringLiteral( "INPUT" ), false );
   distance->setIsDynamic( true );
   distance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "DISTANCE" ), QObject::tr( "Distance between rings" ), QgsPropertyDefinition::DoublePositive ) );
   distance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );