Update package version to 4.21.0

pkg.info

@@ -1,9 +1,24 @@
 name: gtkmm4
 description: The official C++ interface for the popular GUI library GTK (version 4)
-version: 4.20.0
+version: 4.21.0
+revision: 1
 url: https://www.gtkmm.org/
 license: LGPL2.1-or-later
 architecture: any
-depends: ["atkmm", "cairomm-1.16", "gcc-libs", "gdk-pixbuf", "glib", "glibc", "glibmm-2.68", "graphene", "gtk4", "libsigcpp-3.0", "pangomm-2.48", "vulkan-loader"]
-make_depends: ["meson","mm-common"]
 type: source
+depends:
+  - atkmm
+  - cairomm-1.16
+  - gcc-libs
+  - gdk-pixbuf
+  - glib
+  - glibc
+  - glibmm-2.68
+  - graphene
+  - gtk4
+  - libsigcpp-3.0
+  - pangomm-2.48
+  - vulkan-loader
+make_depends:
+  - meson
+  - mm-common