[evolution-data-server] Bump gtk+ requirement to 3.16, due to used functions from that version

[Milan Crha <mcrha src gnome org>]

commit 6b34dd3ad1c077af011dbce65d1aa4e9047fa78d
Author: Milan Crha <mcrha redhat com>
Date:   Wed Nov 11 16:11:13 2020 +0100

    Bump gtk+ requirement to 3.16, due to used functions from that version
    
    Related to https://gitlab.gnome.org/GNOME/evolution-ews/-/issues/134

 CMakeLists.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d18e8d14b..f992aeadb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -89,8 +89,8 @@ set(glib_minimum_version 2.46)
 set(glib_encoded_version GLIB_VERSION_2_46)
 
 # Keep these two definitions in agreement.
-set(gdk_minimum_version 3.10)
-set(gdk_encoded_version GDK_VERSION_3_10)
+set(gdk_minimum_version 3.16)
+set(gdk_encoded_version GDK_VERSION_3_16)
 
 # Keep these two definitions in agreement.
 set(soup_minimum_version 2.58)