Use correct attribute from entrypoint

The type of the entry point objects returned in stevedore has
been changed from`pkg_resources.EntryPoint` to
`importlib.metadata.EntryPoint`[1] and it does not have module_name
attribute.

It also bumps requirements/lower-constraints as stevedore==3.1.0 is
not backward compatible.

[1] https://review.opendev.org/#/c/740515/
Task: 40355
Change-Id: Icd68f6eab73e44406f2ff5073636dcdd111e00ea

heat/common/pluginutils.py

@@ -20,7 +20,7 @@ LOG = logging.getLogger(__name__)
 def log_fail_msg(manager, entrypoint, exception):
     LOG.warning('Encountered exception while loading %(module_name)s: '
                 '"%(message)s". Not using %(name)s.',
-                {'module_name': entrypoint.module_name,
+                {'module_name': entrypoint.module,
                  'message': getattr(exception, 'message',
                                     str(exception)),
                  'name': entrypoint.name})

lower-constraints.txt

@@ -139,7 +139,7 @@ SQLAlchemy==1.0.10
 sqlparse==0.2.4
 statsd==3.2.2
 stestr==2.0.0
-stevedore==1.20.0
+stevedore==3.1.0
 tempest==17.1.0
 Tempita==0.5.2
 tenacity==4.4.0

requirements.txt

@@ -61,6 +61,6 @@ tenacity>=4.4.0 # Apache-2.0
 Routes>=2.3.1 # MIT
 SQLAlchemy!=1.1.5,!=1.1.6,!=1.1.7,!=1.1.8,>=1.0.10 # MIT
 sqlalchemy-migrate>=0.11.0 # Apache-2.0
-stevedore>=1.20.0 # Apache-2.0
+stevedore>=3.1.0 # Apache-2.0
 WebOb>=1.7.1 # MIT
 yaql>=1.1.3 # Apache 2.0 License