Update python dependencies

Change-Id: Ic1ba3152160e9255d14ae66881e452a99930b0d8
diff --git a/ndn-cxx/debian/control b/ndn-cxx/debian/control
index 069a697..093a5da 100644
--- a/ndn-cxx/debian/control
+++ b/ndn-cxx/debian/control
@@ -2,12 +2,12 @@
 Priority: extra
 Maintainer: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 Build-Depends: debhelper (>= 8.0.0),
- python3 (>= 3.5.0),
+ python3 (>= 3.6.0),
  pkg-config (>= 0.26),
  libssl-dev (>=1.0.1),
  libsqlite3-dev (>= 3.7.9),
- python3-sphinx (>= 1.3.6),
  libboost-all-dev (>= 1.53.0),
+ python3-sphinx (>= 1.6.0),
  git
 Standards-Version: 3.9.2
 Section: libs
@@ -18,7 +18,7 @@
 Package: libndn-cxx-dev
 Section: libdevel
 Architecture: i386 amd64 arm64 armel armhf ppc64el
-Depends: python (>= 2.7.0),
+Depends:
  pkg-config (>= 0.26),
  libssl-dev (>=1.0.1),
  libsqlite3-dev (>= 3.7.9),