build: require boost >= 1.71.0

Refs: #5276
Change-Id: I0f179707020fc6e0908af8aeb1d535ca3cd81410
diff --git a/tests/wscript b/tests/wscript
index 2d83303..7ab65d1 100644
--- a/tests/wscript
+++ b/tests/wscript
@@ -1,14 +1,15 @@
 # -*- Mode: python; py-indent-offset: 4; indent-tabs-mode: nil; coding: utf-8; -*-
 
-top = '../'
+top = '..'
 
 def build(bld):
     # common objects that can be shared among all tests
-    bld.objects(target='tests-common',
-                source=bld.path.ant_glob('*.cpp'),
-                features='pch',
-                headers='tests-pch.hpp',
-                use='BOOST_TESTS ndn-cxx')
+    bld.objects(
+        target='tests-common',
+        source=bld.path.ant_glob('*.cpp'),
+        features='pch',
+        headers='tests-pch.hpp',
+        use='BOOST_TESTS ndn-cxx')
 
     bld.recurse('benchmarks')
     bld.recurse('integration')