fix: improve detection of poetry 2 projects (#274)

Projects created with poetry >= 2.0 don't necessarily include a
tool.poetry table in the pyproject.toml. Thus poethepoet cannot
rely on the presence or absence of this table to tell whether
it is appropriate to default to using the PoetryExecutor to run
tasks with poetry's venv.

It seems the best remaining indicator is the content of the
build-system which poetry still configures consistently, although
this is less ideal.

poethepoet/config/config.py

@@ -120,9 +120,14 @@ def verbosity(self) -> int:
 
     @property
     def is_poetry_project(self) -> bool:
-        return (
-            self._project_config.path.name == "pyproject.toml"
-            and "poetry" in self._project_config.full_config.get("tool", {})
+        full_config = self._project_config.full_config
+        return self._project_config.path.name == "pyproject.toml" and (
+            "poetry" in full_config.get("tool", {})
+            or (
+                # Fallback required to work out of the box with some poetry 2.0 projects
+                full_config.get("build-system", {}).get("build-backend", "")
+                == "poetry.core.masonry.api"
+            )
         )
 
     @property

poethepoet/plugin.py

@@ -154,7 +154,7 @@ def _get_config(cls, application: Application) -> "PoeConfig":
         # Try respect poetry's '--directory' if set
         try:
             pyproject_dir = application.poetry.pyproject_path.parent
-        except AttributeError:
+        except (AttributeError, RuntimeError):
             pyproject_dir = None
 
         poe_config = PoeConfig(cwd=pyproject_dir)