update constraint for openstack-release-test to new release 8.4.0

meta: version: 8.4.0
meta: team: Release Management
meta: diff-start: -
meta: series: hibiscus
meta: branch: master
meta: release-type: release
meta: pypi: no
meta: first: yes
meta: release:Author: Elod Illes <elod.illes@est.tech>
meta: release:Commit: Elod Illes <elod.illes@est.tech>
meta: release:Change-Id: Ib4839c30b8d4c10b3ae6639ae14f947662a560d5
meta: release:Workflow+1: Elod Illes <elod.illes@est.tech>
meta: release:Code-Review+2: Elod Illes <elod.illes@est.tech>
Change-Id: I9f5f9107f79422d77f246eb45ff81444ea3a1de1
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

@@ -180,7 +180,7 @@ httpcore===1.0.9
 URLObject===3.0.0
 psycopg2-binary===2.9.11
 glance_store===5.4.0
-openstack-release-test===8.3.0
+openstack-release-test===8.4.0
 requests-mock===1.12.1
 os-apply-config===14.0.1
 gunicorn===25.3.0