Update the UPPER_CONSTRAINTS_FILE for tox

1. Update the UPPER_CONSTRAINTS_FILE for tox[1]
2. Remove unncessary "=="
3. Update some URLs to latest

[1]: http://lists.openstack.org/pipermail/openstack-discuss/2019-May/006478.html

Change-Id: I447fa8594a7f11d5d8ed455353020b6871f596e5

CONTRIBUTING.rst

@@ -1,14 +1,14 @@
 If you would like to contribute to the development of OpenStack, you must
 follow the steps in this page:
 
-   http://docs.openstack.org/infra/manual/developers.html
+   https://docs.openstack.org/infra/manual/developers.html
 
 If you already have a good understanding of how the system works and your
 OpenStack accounts are set up, you can skip to the development workflow
 section of this documentation to learn how changes to OpenStack should be
 submitted for review via the Gerrit tool:
 
-   http://docs.openstack.org/infra/manual/developers.html#development-workflow
+   https://docs.openstack.org/infra/manual/developers.html#development-workflow
 
 Pull requests submitted through GitHub will be ignored.
 

README.rst

@@ -1,6 +1,6 @@
-===============================
+========
 ovsdbapp
-===============================
+========
 
 A library for creating OVSDB applications
 

doc/source/user/index.rst

@@ -1,6 +1,6 @@
-========
+=====
 Usage
-========
+=====
 
 To use ovsdbapp in a project::
 

tox.ini

@@ -11,7 +11,7 @@ setenv =
    OS_TEST_PATH=./ovsdbapp/tests/unit
 install_command = pip install {opts} {packages}
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands = stestr run --slowest {posargs}