Revert "Fix mypy for PgVersion"

This reverts commit 259275f.

test_runner/fixtures/pg_version.py

@@ -23,13 +23,6 @@ class PgVersion(StrEnum):
     # to explicitly rely on the default server version (could be different from pg_version fixture value)
     NOT_SET = "<-POSTRGRES VERSION IS NOT SET->"
 
-    # Allow PgVersion to accept str or int
-    # https://docs.python.org/3.11/library/enum.html#supported-dunder-names
-    @classmethod
-    @override
-    def __new__(cls, value: int | str):
-        return super().__new__(cls, str(value))
-
     # Make it less confusing in logs
     @override
     def __repr__(self) -> str:
@@ -48,20 +41,18 @@ def v_prefixed(self) -> str:
     @classmethod
     @override
     def _missing_(cls, value: object) -> PgVersion | None:
-        if not isinstance(value, str):
-            return None
-
         known_values = {v.value for _, v in cls.__members__.items()}
 
-        # Allow passing version as v-prefixed string (e.g. "v14")
-        if value.lower().startswith("v") and (v := value[1:]) in known_values:
-            return cls(v)
-        # Allow passing version as an int (in __new__ it's converted to str)
-        # (e.g. 15 or 150002, both will be converted to PgVersion.V15)
-        elif value.isdigit() and (v := value[:2]) in known_values:
-            return cls(v)
-        else:
-            return None
+        # Allow passing version as a string with "v" prefix (e.g. "v14")
+        if isinstance(value, str) and value.lower().startswith("v") and value[1:] in known_values:
+            return cls(value[1:])
+        # Allow passing version as an int (e.g. 15 or 150002, both will be converted to PgVersion.V15)
+        elif isinstance(value, int) and str(value)[:2] in known_values:
+            return cls(str(value)[:2])
+
+        # Make mypy happy
+        # See https://github.com/python/mypy/issues/3974
+        return None
 
 
 DEFAULT_VERSION: PgVersion = PgVersion.V16