Switch to the master constraint in tox.ini

To releas a new tag for Tempest 2023.2, we modified the
compatible constraint in tox.ini
- https://review.opendev.org/c/openstack/tempest/+/874359/1

As new tag is released now so we can switch back to the master
constraint in tox.ini.

Change-Id: I431ec42d81c4d2a95d6f541c794607de1f9cadb8
diff --git a/tox.ini b/tox.ini
index c910b51..e809f1c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,7 +9,7 @@
     OS_TEST_PATH=./tempest/test_discover
     OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:1200}
 deps =
-    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.2}
+    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/requirements.txt
 
 [testenv]
@@ -40,7 +40,7 @@
 allowlist_externals =
     find
 deps =
-    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.2}
+    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
 commands =
@@ -337,7 +337,7 @@
 
 [testenv:venv]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.2}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands = {posargs}
@@ -351,7 +351,7 @@
 
 [testenv:docs]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.2}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
 commands =
   sphinx-apidoc -f -o doc/source/tests/compute tempest/api/compute
@@ -438,7 +438,7 @@
 
 [testenv:releasenotes]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.2}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf releasenotes/build