gnu: libchamplain: Update to 0.12.20.

* gnu/packages/gnome.scm (libchamplain): Update to 0.12.20.
[build-system]: Change to meson-build-system.
[propagated-inputs]{libsoup}: Use libsoup 2.

gnu/packages/gnome.scm

@@ -5989,7 +5989,7 @@ OpenGL-based interactive canvas library.")
 (define-public libchamplain
   (package
     (name "libchamplain")
-    (version "0.12.16")
+    (version "0.12.20")
     (source (origin
               (method url-fetch)
               (uri (string-append
@@ -5997,15 +5997,14 @@ OpenGL-based interactive canvas library.")
                     version ".tar.xz"))
               (sha256
                (base32
-                "13chvc2n074i0jw5jlb8i7cysda4yqx58ca6y3mrlrl9g37k2zja"))))
-    (build-system gnu-build-system)
-    (arguments '(#:configure-flags '("--enable-vala")))
+                "0rihpb0npqpihqcdz4w03rq6xl7jdckfqskvv9diq2hkrnzv8ch2"))))
+    (build-system meson-build-system)
     (native-inputs
      `(("gobject-introspection" ,gobject-introspection)
        ("pkg-config" ,pkg-config)
        ("vala" ,vala)))
     (propagated-inputs
-     `(("libsoup" ,libsoup)
+     `(("libsoup" ,libsoup-minimal-2)
        ("sqlite" ,sqlite)
        ("clutter" ,clutter)
        ("clutter-gtk" ,clutter-gtk)