update constraint for horizon to new release 25.6.0

meta: version: 25.6.0
meta: team: horizon
meta: diff-start: -
meta: series: gazpacho
meta: branch: master
meta: release-type: release
meta: pypi: no
meta: first: yes
meta: release:Author: Pierre Riteau <pierre@stackhpc.com>
meta: release:Commit: Tatiana Ovchinnikova <t.v.ovtchinnikova@gmail.com>
meta: release:Change-Id: I753809250009ddc57ff9ddfec1a15220b2b1ab03
meta: release:Code-Review+2: Elod Illes <elod.illes@est.tech>
meta: release:Workflow+1: Elod Illes <elod.illes@est.tech>
meta: release:Code-Review+1: Takashi Kajinami <kajinamit@oss.nttdata.com>
meta: release:Code-Review+1: Michal Nasiadka <mnasiadka@gmail.com>
meta: release:Code-Review+1: Maksim Malchuk <maksim.malchuk@gmail.com>
meta: release:Code-Review+1: Pierre Riteau <pierre@stackhpc.com>
meta: release:Code-Review+1: Ivan Anfimov <lazekteam@gmail.com>
Change-Id: I65fda08e5c1ec9478c3b31c71d075da76e9016b1
Signed-off-by: OpenStack Proposal Bot <openstack-infra@lists.openstack.org>
Generated-By: openstack/project-config:roles/copy-release-tools-scripts/files/release-tools/update_constraints.sh

Author: OpenStack Proposal Bot

upper-constraints.txt

@@ -111,7 +111,7 @@ debtcollector===3.0.0
 responses===0.26.0
 backports.strenum===1.3.1;python_version=='3.10'
 croniter===6.0.0
-horizon===25.5.1
+horizon===25.6.0
 octavia-lib===3.11.0
 python-watcherclient===4.10.0
 MarkupSafe===3.0.3