more pydantic way of forcing SETTINGS.external.count to None

kiwi_simple_metrics/settings/metric.py

@@ -89,14 +89,11 @@ class ExternalMS(MetricSettings):
     enabled: bool = False
     threshold: float = 0
 
+    # always include all defined external values!
+    count: None = None
+
     # path to executable files
     executables: list[FilePath] = []
 
     # wait at most this many seconds for each executable
     timeout: int = 60
-
-    @field_validator("count", mode="after")
-    @classmethod
-    def force_none(cls, _) -> int | None:
-        """Don't accept a `count` value for the external metric!"""
-        return None