[caribou] Bump required vala version to 0.13

[Dan Winship <danw src gnome org>]

commit d1cde5b90684f710cbce8a88dcfc5a1b0620cad6
Author: Dan Winship <danw gnome org>
Date:   Fri Aug 12 09:27:57 2011 -0400

    Bump required vala version to 0.13
    
    Needed to get the fix for bug 644275 so that the call to
    Bus.get_proxy_async() will compile correctly.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=655047

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 721f317..948a93d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,7 +36,7 @@ PKG_CHECK_MODULES(CARIBOU, [
 AC_SUBST(CARIBOU_CFLAGS)
 AC_SUBST(CARIBOU_LIBS)
 
-AM_PROG_VALAC([0.9.3])
+AM_PROG_VALAC([0.13])
 AC_SUBST(VALAC)
 AC_SUBST(VALAFLAGS)