Prepare release 0.5.6

Change-Id: Ia2372b6ea63b5c3c5cdfb0f2d9990b6537e47c74
diff --git a/wscript b/wscript
index 0249c0d..bae5eaf 100644
--- a/wscript
+++ b/wscript
@@ -4,7 +4,7 @@
 import subprocess
 from waflib import Context, Logs
 
-VERSION = '0.5.5'
+VERSION = '0.5.6'
 APPNAME = 'ChronoSync'
 GIT_TAG_PREFIX = ''
 
@@ -34,7 +34,7 @@
     conf.find_program(['pkgconf', 'pkg-config'], var='PKGCONFIG')
 
     pkg_config_path = os.environ.get('PKG_CONFIG_PATH', f'{conf.env.LIBDIR}/pkgconfig')
-    conf.check_cfg(package='libndn-cxx', args=['libndn-cxx >= 0.8.1', '--cflags', '--libs'],
+    conf.check_cfg(package='libndn-cxx', args=['libndn-cxx >= 0.9.0', '--cflags', '--libs'],
                    uselib_store='NDN_CXX', pkg_config_path=pkg_config_path)
 
     conf.check_boost(lib='iostreams', mt=True)