fix: plots in popout window not scaled propertly

This is caused by Voila 0.4.0 which is now based on ipywidgets 8.
The Layout widget of v7 could not be created, resulting in the
height of the plots not being set.

See: #1787

setup.cfg

@@ -32,7 +32,7 @@ install_requires =
     ipysplitpanes>=0.1.0
     ipygoldenlayout>=0.3.0
     ipywidgets<8.0
-    voila>=0.3.5
+    voila>=0.3.5,<0.4
     pyyaml>=5.4.1
     specutils>=1.7.0
     specreduce>=1.2.0,<1.3.0