Update python dependencies

Change-Id: Ic1ba3152160e9255d14ae66881e452a99930b0d8
diff --git a/libpsync/debian/control b/libpsync/debian/control
index d7fce44..036d59f 100644
--- a/libpsync/debian/control
+++ b/libpsync/debian/control
@@ -2,11 +2,11 @@
 Priority: optional
 Maintainer: Ashlesh Gawande <agawande@memphis.edu>
 Build-Depends: debhelper (>= 8.0.0),
- python3 (>= 3.5.0),
+ python3 (>= 3.6.0),
  pkg-config (>= 0.26),
- python3-sphinx (>= 1.1.3),
  libboost-all-dev (>= 1.53.0),
  libndn-cxx-dev (>= 0.7.0),
+ python3-sphinx (>= 1.6.0),
  git
 Standards-Version: 4.1.2
 Section: libs