update constraint for taskflow to new release 5.12.0

meta: version: 5.12.0
meta: team: oslo
meta: diff-start: -
meta: series: epoxy
meta: branch: master
meta: release-type: release
meta: pypi: yes
meta: first: no
meta: release:Author: Kacper <kkulakow@redhat.com>
meta: release:Commit: Kacper <kkulakow@redhat.com>
meta: release:Change-Id: I2e695d29dc07e5b2e898328c7f0fed7c383a58da
meta: release:Code-Review+2: Dr. Jens Harbott <frickler@offenerstapel.de>
meta: release:Code-Review+2: Thierry Carrez <thierry@openstack.org>
meta: release:Code-Review+1: Takashi Kajinami <kajinamit@oss.nttdata.com>
meta: release:Workflow+1: Thierry Carrez <thierry@openstack.org>
Change-Id: Iddc3e75059e96dfb439834124ac4e12c5a2a46ff

Author: OpenStack Proposal Bot

upper-constraints.txt

@@ -146,7 +146,7 @@ sphinxcontrib.datatemplates===0.11.0
 jsonpath-rw===1.4.0
 prettytable===3.14.0
 vine===5.1.0
-taskflow===5.11.0
+taskflow===5.12.0
 arrow===1.3.0
 semantic-version===2.10.0
 async-timeout===5.0.1;python_version=='3.10'