CI: Remove upper-constraints in linters tox job

j2lint 1.2.0 requires rich<15 and u-c bumped it to 15.0.0, so things
are failing right now - but we don't need u-c for linters job

Change-Id: Ie14c11e299da1e505d379ad35928cc62929a678f
Signed-off-by: Michal Nasiadka <mnasiadka@gmail.com>

tox.ini

@@ -97,7 +97,6 @@ setenv =
   ANSIBLE_ROLES_PATH = {toxinidir}/ansible/roles
 
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/lint-requirements.txt
 allowlist_externals = bash