Limit the usage of upper-constraints

molecule[1] is not compatible with upper-constraints and it breaks
the molecule installation in the tox venv due to version conflicts
coming from upper-constraints.

In order to fix that, we are limiting the usage of uc only for
docs and release notes.

[1]. ansible/molecule#3244

Related-Bug: #1942704

Signed-off-by: Amol Kahat <amolkahat@gmail.com>
CoAuthored-by: Chandan Kumar (raukadah) <chkumar@redhat.com>
Change-Id: Ia35c83c13bd9e38384327630374b3aacebe9007b

tox.ini

@@ -5,7 +5,7 @@ skipsdist = True
 
 [testenv]
 usedevelop = True
-install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt} {opts} {packages}
+install_command = pip install {opts} {packages}
 passenv = *
 setenv =
   VIRTUAL_ENV={envdir}
@@ -92,13 +92,16 @@ commands =
 
 [testenv:releasenotes]
 basepython = python3
-deps = -r{toxinidir}/doc/requirements.txt
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -r{toxinidir}/doc/requirements.txt
 commands =
     sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
 [testenv:docs]
 basepython = python3
 deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r {toxinidir}/doc/requirements.txt
 commands=
     doc8 doc