Update gtksourceview in Flatpak manifest

See flathub/com.inform7.IDE#17

Author: ptomato

build-aux/com.inform7.IDE.yml

@@ -99,9 +99,14 @@ modules:
       - -Dinstall_tests=false
     sources:
       - type: archive
-        url: "https://download.gnome.org/sources/gtksourceview/\
-          4.8/gtksourceview-4.8.2.tar.xz"
-        sha256: 842de7e5cb52000fd810e4be39cd9fe29ffa87477f15da85c18f7b82d45637cc
+        url: https://download.gnome.org/sources/gtksourceview/4.8/gtksourceview-4.8.4.tar.xz
+        sha256: 7ec9d18fb283d1f84a3a3eff3b7a72b09a10c9c006597b3fbabbb5958420a87d
+        x-checker-data:
+          type: gnome
+          name: gtksourceview
+          versions:
+            <: 5.0.0
+          version-scheme: odd-minor-is-unstable
   - name: ratify
     cleanup:
       - /include