1.17.6 breaks build Pipeline (NameError: name 'Post' is not defined)

[thies23]

We build mkdocs pages via GitLab Build Pipeline.
Vanilla mkdocs, plugin installed via pip. No other plugins.

When building with 1.17.6 the build fails with this output:

$ mkdocs build
Traceback (most recent call last):
  File "/usr/local/bin/mkdocs", line 8, in <module>
    sys.exit(cli())
             ^^^^^
  File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1462, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1383, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1850, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1246, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 814, in invoke
    return callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/__main__.py", line 285, in build_command
    cfg = config.load_config(**kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/base.py", line 374, in load_config
    errors, warnings = cfg.validate()
                       ^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/base.py", line 231, in validate
    run_failed, run_warnings = self._validate()
                               ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/base.py", line 188, in _validate
    self[key] = config_option.validate(value)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/config_options.py", line 186, in validate
    return self.run_validation(value)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/config_options.py", line 1065, in run_validation
    self.load_plugin_with_namespace(name, cfg)
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/config_options.py", line 1103, in load_plugin_with_namespace
    return (name, self.load_plugin(name, config))
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/mkdocs/config/config_options.py", line 1121, in load_plugin
    plugin_cls = self.installed_plugins[name].load()
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/importlib/metadata/__init__.py", line 202, in load
    module = import_module(match.group('module'))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1206, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1178, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1149, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/usr/local/lib/python3.11/dist-packages/mkdocs_rss_plugin/plugin.py", line 34, in <module>
    from mkdocs_rss_plugin.integrations.theme_material_blog_plugin import (
  File "/usr/local/lib/python3.11/dist-packages/mkdocs_rss_plugin/integrations/theme_material_blog_plugin.py", line 43, in <module>
    class IntegrationMaterialBlog(IntegrationMaterialThemeBase):
  File "/usr/local/lib/python3.11/dist-packages/mkdocs_rss_plugin/integrations/theme_material_blog_plugin.py", line 135, in IntegrationMaterialBlog
    def is_page_a_blog_post(self, mkdocs_page: Post | MkdocsPageSubset) -> bool:
                                               ^^^^
NameError: name 'Post' is not defined

Pinning to 1.17.5 fixes the issue.

[Guts]

Thanks @td00 for taking time to report here.

[Guts]

Fixed in 1.17.7: https://github.com/Guts/mkdocs-rss-plugin/releases/tag/1.17.7