mainWindow: Remove shadow from ScrolledWindow

Our ScrolledWindow was using Gtk.ShadowType.In, causing a nasty border effect on the window. By defaulting to ShadowType.None we get rid of this border.
3 jobs for <span class="ref-name">wip/christopherdavis/use-no-shadow-for-scrolledwindow</span> in 1 minute and 29 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #193798
flatpak

00:00:37

 
  Deploy
passed #193799
review

00:00:25

passed #193800
allowed to fail manual
stop_review

00:00:25