Fix Trajectory.radial_distribution_between_species() error (344)

Author: stefsmeets

src/gemdat/trajectory.py

@@ -749,6 +749,7 @@ def metrics(self) -> TrajectoryMetrics:
 
         return TrajectoryMetrics(trajectory=self)
 
+    @plot_backend
     def radial_distribution_between_species(self, *, module, **kwargs) -> RDFData:
         """See [gemdat.rdf.radial_distribution_between_species][] for more
         info."""