put RectangularSource in import

Author: Jammy2211

autoarray/inversion/pixelization/mesh/__init__.py

@@ -1,5 +1,6 @@
 from .abstract import AbstractMesh as Mesh
 from .rectangular import RectangularMagnification
+from .rectangular import RectangularSource
 from .rectangular_uniform import RectangularUniform
 from .voronoi import Voronoi
 from .delaunay import Delaunay