Fix pylint zuul failure

The starlingx-staging repo was incorrectly being pointed at for tox
pylint dependencies.  The dependencies were colliding with
dependencies from other repos.

That repo is not used anymore, instead the latest stable stein is used.

This change points at the most recently released stable/stein horizon
(15.0.2) in the requirements.

This change has no effect on build or deployment, only tox.

The upper constraints zuul job overrides the stein upper constraints,
and therefore the oslo concurrency 4.0.0 released Feb 3rd is no
longer triggering a failed tox job.

Closes-Bug: 1861932
Change-Id: I3c3fd22993faf47c7e3c32bae18a7f2ab1dd031c
Signed-off-by: albailey <Al.Bailey@windriver.com>

tox.ini

@@ -9,8 +9,8 @@ stxdir = {toxinidir}/..
 [testenv]
 install_command = pip install \
     -v -v -v \
-    -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt}  \
-    -U {opts} {packages}
+    -c https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt  \
+    {opts} {packages}
 
 setenv = VIRTUAL_ENV={envdir}
          OS_STDOUT_CAPTURE=1
@@ -56,7 +56,6 @@ basepython = python2.7
 usedevelop = False
 skip_install = True
 deps = {[testenv]deps}
-    git+git://github.com/starlingx-staging/stx-horizon.git
     -e{[tox]stxdir}/{env:STX_DC_CLIENT}/distributedcloud-client
     -e{[tox]stxdir}/config/sysinv/cgts-client/cgts-client
     -e{[tox]stxdir}/config/sysinv/sysinv/sysinv
@@ -65,6 +64,7 @@ deps = {[testenv]deps}
     -e{[tox]stxdir}/nfv/nfv/nfv-client
     -e{[tox]stxdir}/ha/service-mgmt-client/sm-client
     -e{[tox]stxdir}/utilities/ceph/python-cephclient/python-cephclient
+    horizon==15.2.0
     requests-toolbelt
     pylint
 commands =