add _dbm and _gdbm to align naming of error types with runtime (#12978)

stdlib/_gdbm.pyi

@@ -0,0 +1,47 @@
+import sys
+from _typeshed import ReadOnlyBuffer, StrOrBytesPath
+from types import TracebackType
+from typing import TypeVar, overload
+from typing_extensions import Self, TypeAlias
+
+if sys.platform != "win32":
+    _T = TypeVar("_T")
+    _KeyType: TypeAlias = str | ReadOnlyBuffer
+    _ValueType: TypeAlias = str | ReadOnlyBuffer
+
+    open_flags: str
+
+    class error(OSError): ...
+    # Actual typename gdbm, not exposed by the implementation
+    class _gdbm:
+        def firstkey(self) -> bytes | None: ...
+        def nextkey(self, key: _KeyType) -> bytes | None: ...
+        def reorganize(self) -> None: ...
+        def sync(self) -> None: ...
+        def close(self) -> None: ...
+        if sys.version_info >= (3, 13):
+            def clear(self) -> None: ...
+
+        def __getitem__(self, item: _KeyType) -> bytes: ...
+        def __setitem__(self, key: _KeyType, value: _ValueType) -> None: ...
+        def __delitem__(self, key: _KeyType) -> None: ...
+        def __contains__(self, key: _KeyType) -> bool: ...
+        def __len__(self) -> int: ...
+        def __enter__(self) -> Self: ...
+        def __exit__(
+            self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+        ) -> None: ...
+        @overload
+        def get(self, k: _KeyType) -> bytes | None: ...
+        @overload
+        def get(self, k: _KeyType, default: _T) -> bytes | _T: ...
+        def keys(self) -> list[bytes]: ...
+        def setdefault(self, k: _KeyType, default: _ValueType = ...) -> bytes: ...
+        # Don't exist at runtime
+        __new__: None  # type: ignore[assignment]
+        __init__: None  # type: ignore[assignment]
+
+    if sys.version_info >= (3, 11):
+        def open(filename: StrOrBytesPath, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...
+    else:
+        def open(filename: str, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...