Switch to libsoup 3

This is a compatibility cliff. All dependencies that still use libsoup 2
must switch to libsoup 3 now or die. Sorry, but grilo does not provide
parallel-installable versions.

grilo.spec

@@ -18,7 +18,7 @@ BuildRequires:  vala >= 0.27.1
 BuildRequires:  gtk-doc
 BuildRequires:  gobject-introspection-devel >= 0.9.0
 BuildRequires:  libxml2-devel
-BuildRequires:  libsoup-devel
+BuildRequires:  libsoup3-devel
 BuildRequires:  glib2-devel
 
 # For the test UI
@@ -48,8 +48,7 @@ general and API documentation.
 
 %build
 %meson \
-    -Denable-gtk-doc=true \
-    -Dsoup3=false
+    -Denable-gtk-doc=true
 
 %meson_build