Do not depend on python-openstackclient

OpenStack client is not a runtime dependency of inspector client,
and having it in requirements just brings in many dependencies
which might not be needed at all when using the Python API of the client
only (for example in server-side applications, like ironic-conductor).

Although dependency on osc-lib is enough for unit and functional tests
to pass.

Also, add a setuptools 'extra' so that users can install openstackclient
together with inspector client:

    pip install python-ironic-inspector-client[cli]

Co-Authored-By: Pavlo Shchelokovskyy <shchelokovskyy@gmail.com>
Closes-Bug: #1562023
Change-Id: I430549146a25eb05cc7905b221abb81d144e0f8b

releasenotes/notes/drop-osc-client-requirements-efb31b432ddbb370.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    ``python-openstackclient`` is no more a requirement for
+    ``python-ironic-inspector-client``. If you wish to use
+    **ironic-inspector** cli, you should install
+    ``python-openstackclient`` manually or use setuptools "extra"::
+
+         pip install python-ironic-inspector-client[cli]

requirements.txt

@@ -6,6 +6,5 @@ osc-lib>=1.2.0 # Apache-2.0
 oslo.i18n>=2.1.0 # Apache-2.0
 oslo.utils>=3.20.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
-python-openstackclient>=3.3.0 # Apache-2.0
 requests!=2.12.2,!=2.13.0,>=2.10.0 # Apache-2.0
 six>=1.9.0 # MIT

setup.cfg

@@ -49,3 +49,7 @@ warnerrors = True
 all_files = 1
 build-dir = doc/build
 source-dir = doc/source
+
+[extras]
+cli =
+    python-openstackclient>=3.3.0 # Apache-2.0