use __new__ in .pyi for Rust types (#743)

Author: davidhewitt

python/pydantic_core/_pydantic_core.pyi

@@ -58,7 +58,7 @@ class Some(Generic[_T]):
 
 @final
 class SchemaValidator:
-    def __init__(self, schema: CoreSchema, config: CoreConfig | None = None) -> None: ...
+    def __new__(cls, schema: CoreSchema, config: CoreConfig | None = None) -> Self: ...
     @property
     def title(self) -> str: ...
     def validate_python(
@@ -103,7 +103,7 @@ _IncEx: TypeAlias = set[int] | set[str] | dict[int, _IncEx] | dict[str, _IncEx]
 
 @final
 class SchemaSerializer:
-    def __init__(self, schema: CoreSchema, config: CoreConfig | None = None) -> None: ...
+    def __new__(cls, schema: CoreSchema, config: CoreConfig | None = None) -> Self: ...
     def to_python(
         self,
         value: Any,
@@ -164,7 +164,7 @@ def to_jsonable_python(
 ) -> Any: ...
 
 class Url(SupportsAllComparisons):
-    def __init__(self, url: str) -> None: ...
+    def __new__(cls, url: str) -> Self: ...
     @property
     def scheme(self) -> str: ...
     @property
@@ -189,7 +189,7 @@ class Url(SupportsAllComparisons):
     def __deepcopy__(self, memo: dict) -> str: ...
 
 class MultiHostUrl(SupportsAllComparisons):
-    def __init__(self, url: str) -> None: ...
+    def __new__(cls, url: str) -> Self: ...
     @property
     def scheme(self) -> str: ...
     @property
@@ -233,9 +233,9 @@ class ValidationError(ValueError):
 
 @final
 class PydanticCustomError(ValueError):
-    def __init__(
-        self, error_type: LiteralString, message_template: LiteralString, context: dict[str, Any] | None = None
-    ) -> None: ...
+    def __new__(
+        cls, error_type: LiteralString, message_template: LiteralString, context: dict[str, Any] | None = None
+    ) -> Self: ...
     @property
     def context(self) -> dict[str, Any] | None: ...
     @property
@@ -246,9 +246,9 @@ class PydanticCustomError(ValueError):
 
 @final
 class PydanticKnownError(ValueError):
-    def __init__(
-        self, error_type: ErrorType, context: dict[str, str | int | float | decimal.Decimal] | None = None
-    ) -> None: ...
+    def __new__(
+        cls, error_type: ErrorType, context: dict[str, str | int | float | decimal.Decimal] | None = None
+    ) -> Self: ...
     @property
     def context(self) -> dict[str, str | int | float] | None: ...
     @property
@@ -259,23 +259,23 @@ class PydanticKnownError(ValueError):
 
 @final
 class PydanticOmit(Exception):
-    def __new__(self) -> PydanticOmit: ...
+    def __new__(cls) -> Self: ...
 
 @final
 class PydanticUseDefault(Exception):
-    def __new__(self) -> PydanticUseDefault: ...
+    def __new__(cls) -> Self: ...
 
 @final
 class PydanticSerializationError(ValueError):
-    def __init__(self, message: str) -> None: ...
+    def __new__(cls, message: str) -> Self: ...
 
 @final
 class PydanticSerializationUnexpectedValue(ValueError):
-    def __init__(self, message: str | None = None) -> None: ...
+    def __new__(cls, message: str | None = None) -> Self: ...
 
 @final
 class ArgsKwargs:
-    def __init__(self, args: tuple[Any, ...], kwargs: dict[str, Any] | None = None) -> None: ...
+    def __new__(cls, args: tuple[Any, ...], kwargs: dict[str, Any] | None = None) -> Self: ...
     @property
     def args(self) -> tuple[Any, ...]: ...
     @property