[gnome-builder] build: drop gtksourceview-3 compat style schemes

[Christian Hergert <chergert src gnome org>]

commit a671a65c9564173e1e455bbafa30f2ff8aa095c7
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 27 15:16:17 2020 -0700

    build: drop gtksourceview-3 compat style schemes
    
    We don't really need to be installing these anymore, 4.x is quite old at
    this point.

 data/style-schemes/meson.build | 7 -------
 1 file changed, 7 deletions(-)
---
diff --git a/data/style-schemes/meson.build b/data/style-schemes/meson.build
index 786c508e0..128a42ade 100644
--- a/data/style-schemes/meson.build
+++ b/data/style-schemes/meson.build
@@ -2,10 +2,3 @@ install_data([
   'builder.style-scheme.xml',
   'builder-dark.style-scheme.xml',
 ], install_dir: join_paths(get_option('datadir'), 'gtksourceview-4/styles'))
-
-# For applications using legacy gtksourceview-3.0, like gedit up until
-# recently, install the style-schemes for them too.
-install_data([
-  'builder.style-scheme.xml',
-  'builder-dark.style-scheme.xml',
-], install_dir: join_paths(get_option('datadir'), 'gtksourceview-3.0/styles'))