[seahorse] Bump minimal GTK+ version to 3.22.

[Niels De Graef <nielsdg src gnome org>]

commit 97774fe6ae7e96fcfd4cd53baf4f8bdabec246d1
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Sun Mar 11 12:47:00 2018 +0100

    Bump minimal GTK+ version to 3.22.
    
    The code wouldn't even compile anymore with 3.4, so might as well bump
    it to the last stable version of the 3 series (which is available on the
    latest version of all major distro's).

 meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index ae30696..2c99c2e 100644
--- a/meson.build
+++ b/meson.build
@@ -42,7 +42,7 @@ glib_deps = [
   dependency('gio-2.0',     version: '>=' + min_glib_version),
   dependency('gmodule-2.0', version: '>=' + min_glib_version),
 ]
-gtk = dependency('gtk+-3.0', version: '>= 3.4.0')
+gtk = dependency('gtk+-3.0', version: '>= 3.22.0')
 gcr = dependency('gcr-3',       version: '>=' + min_gcr_version)
 gcr_ui = dependency('gcr-ui-3', version: '>=' + min_gcr_version)
 libsecret = dependency('libsecret-1', version: '>= 0.16')