Prepare release 0.4.0

Change-Id: I361b0a37f48c729b31ea6a61aefb513c8d3d670f
diff --git a/wscript b/wscript
index b368414..59bb70f 100644
--- a/wscript
+++ b/wscript
@@ -3,7 +3,7 @@
 from waflib import Context, Logs, Utils
 import os, subprocess
 
-VERSION = '0.3.0'
+VERSION = '0.4.0'
 APPNAME = 'PSync'
 GIT_TAG_PREFIX = ''
 
@@ -47,7 +47,7 @@
     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 >= 0.8.0', '--cflags', '--libs'],
+    conf.check_cfg(package='libndn-cxx', args=['libndn-cxx >= 0.8.1', '--cflags', '--libs'],
                    uselib_store='NDN_CXX', pkg_config_path=pkg_config_path)
 
     boost_libs = ['system', 'iostreams']