Fix OSA_VERSION during upgrades

Installing OSA in editable mode no longer produce egg-info and wheels,
which results in existance of stale egg-info which returns an old
version for openstack-ansible package.

As we do `cd ${OSA_CLONE_DIR}` this is appended to PATH, making
`importlib` to respect stale egg-info rather then actually installed
version from venv.

On top of that we add a simple pyproject.toml to define the build
backend of pbr to detect package versioning correctly during
installation, as otherwise behavior may be unexpected [1] due to
deprecation.

[1] https://github.com/pypa/pip/issues/11457

Closes-Bug: #2137630
Change-Id: I33c4cd030985a360570202b78e9d6f23f72edbb0
Signed-off-by: Dmitriy Rabotyagov <dmitriy.rabotyagov@cleura.com>

pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+requires = ["pbr>=6.1.1"]
+build-backend = "pbr.build"

releasenotes/notes/fixed-osa-version-detection-59ea42b9f2f55914.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    OpenStack-Ansible and venv version detection is fixed for environments
+    which were upgraded from pre-Flamingo releases.

scripts/bootstrap-ansible.sh

@@ -135,7 +135,7 @@ if [ "${SETUP_ARA}" == "true" ]; then
 fi
 
 # Get current code version (this runs at the root of OSA clone)
-export CURRENT_OSA_VERSION=$(cd ${OSA_CLONE_DIR}; /opt/ansible-runtime/bin/python -c "from importlib.metadata import version; print(version('openstack-ansible'))")
+export CURRENT_OSA_VERSION=$(cd /tmp; /opt/ansible-runtime/bin/python -c "from importlib.metadata import version; print(version('openstack-ansible'))")
 
 # Ensure that Ansible binaries run from the venv
 pushd /opt/ansible-runtime/bin

setup.py

@@ -16,5 +16,5 @@
 import setuptools
 
 setuptools.setup(
-    setup_requires=['pbr>=2.0.0'],
+    setup_requires=['pbr>=6.1.1'],
     pbr=True)