[meld/flatpak-ci] Update dependency list in meson build

[Kai Willadsen <kaiw src gnome org>]

commit 93505d96dd441ee210ed0c691c49b7ecbc8f1705
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sat Dec 21 06:51:01 2019 +1000

    Update dependency list in meson build
    
    It's annoying to have to keep these in sync, but that's the price of
    being able to run uninstalled.

 meson.build | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/meson.build b/meson.build
index 556b6b9a..ff9abbcd 100644
--- a/meson.build
+++ b/meson.build
@@ -13,9 +13,14 @@ if not python3.found()
     error('Python 3 is required to build and use Meld')
 endif
 
+# These requirements are kept in both `bin/meld` and `meson.build`. If you
+# update one, update the other.
+python3.language_version.version_compare('>= 3.6')
 dependency('gtk+-3.0', version: '>= 3.20')
 dependency('glib-2.0', version: '>= 2.48')
 dependency('gtksourceview-4', version: '>= 4.0.0')
+dependency('pygobject-3.0', version: '>= 3.30')
+dependency('py3cairo', version: '>= 1.15.0')
 
 
 if get_option('profile') == 'Devel'