debian, utils: switch to python 3

Make build and external tests work with python3, so we can drop
the python2 dependency.

This should be merged shortly after osmo-python-tests was migrated to
python3, and the jenkins build slaves were (automatically) updated to
have the new osmo-python-tests installed.

Related: OS#2819
Depends: osmo-python-tests I3ffc3519bf6c22536a49dad7a966188ddad351a7
Change-Id: I84ef43f700e125c7a65f92347f12844e07e65655
diff --git a/debian/control b/debian/control
index 6c9cfae..cf7a853 100644
--- a/debian/control
+++ b/debian/control
@@ -16,7 +16,7 @@
                pkg-config,
                libtalloc-dev,
                libsctp-dev,
-               python (>= 2.7.6)
+               python3
 Standards-Version: 3.9.8
 Vcs-Git: git://git.osmocom.org/libosmocore.git
 Vcs-Browser: http://git.osmocom.org/libosmocore/