Bump version to 3.21.4

Update NEWS.

NEWS

@@ -1,3 +1,26 @@
+3.21.4
+======
+* overview: Fix switching workspaces when scrolling on non-primary monitors
+  [Florian; #766883, #768316]
+* Fix crash when using screen recorder under wayland [Rui; #767001]
+* Update theme on video memory purge errors [Rui; #739178]
+* Free old backgrounds immediately [Hyungwon; #766353]
+* Add support for system upgrades to end session dialog [Kalev; #763611]
+* Fix maximized windows flickering to the wrong size on restart [Owen; #761566]
+* Hide ignored events in calendar as well [Florian; #768538]
+* calendar: Only hide dismissed occurrence of recurring event [Florian; #748226]
+* Provide org.freedesktop.impl.portal.access implementation [Florian; #768669]
+* Misc. bug fixes and cleanups [Rui, Florian, Marinus, Jonas; #767954, #768317,
+  #746867, #762206, #768956, #768979]
+
+Contributors:
+  Jonas Ådahl, Piotr Drąg, Hyungwon Hwang, Kalev Lember, Rui Matos,
+  Florian Müllner, Marinus Schraal, Owen W. Taylor
+
+Translations:
+  Andika Triwidada [id], Daniel Mustieles [es], Bruce Cowan [en_GB],
+  Dušan Kazik [sk], Piotr Drąg [pl], Chao-Hsiung Liao [zh_HK]
+
 3.21.3
 ======
  * Do not disable suspend action when locked [Florian; #725960]

configure.ac

@@ -1,5 +1,5 @@
 AC_PREREQ(2.63)
-AC_INIT([gnome-shell],[3.21.3],[https://bugzilla.gnome.org/enter_bug.cgi?product=gnome-shell],[gnome-shell])
+AC_INIT([gnome-shell],[3.21.4],[https://bugzilla.gnome.org/enter_bug.cgi?product=gnome-shell],[gnome-shell])
 AX_IS_RELEASE([git-directory])
 
 AC_CONFIG_HEADERS([config.h])
@@ -77,7 +77,7 @@ AC_MSG_RESULT($enable_systemd)
 CLUTTER_MIN_VERSION=1.21.5
 GOBJECT_INTROSPECTION_MIN_VERSION=1.45.4
 GJS_MIN_VERSION=1.39.0
-MUTTER_MIN_VERSION=3.21.3
+MUTTER_MIN_VERSION=3.21.4
 GTK_MIN_VERSION=3.15.0
 GIO_MIN_VERSION=2.45.3
 LIBECAL_MIN_VERSION=3.5.3