Widen _validate_params parameter annotation to object

The annotation was ``Sequence[Any] | None`` but the function's
job is to REJECT non-sequence shapes (Mapping, set, frozenset)
at runtime. Static-type tools silenced the very inputs the
function exists to reject and admitted some it raises on —
the worst-of-both-worlds for a runtime type-gate. Test sites
carried ``# type: ignore[arg-type]`` for the rejection-path
inputs.

The dbapi sibling ``_reject_non_sequence_params`` already uses
``params: object`` for the same shape; mirror that. Drop the
test-side ``# type: ignore[arg-type]`` comments.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqliteclient/connection.py

@@ -1523,7 +1523,7 @@ async def _bounded_drain() -> None:
             self._invalidation_cause = cause
 
     @staticmethod
-    def _validate_params(params: Sequence[Any] | None) -> None:
+    def _validate_params(params: object) -> None:
         """Reject non-sequence / scalar-iterable param containers.
 
         The qmark paramstyle wants an ordered sequence of positional

tests/test_validate_params_richer.py

@@ -32,15 +32,15 @@ def test_rejects_memoryview(self) -> None:
 
     def test_rejects_dict(self) -> None:
         with pytest.raises(DataError, match="mapping"):
-            _make_conn()._validate_params({"a": 1})  # type: ignore[arg-type]
+            _make_conn()._validate_params({"a": 1})
 
     def test_rejects_set(self) -> None:
         with pytest.raises(DataError, match="set"):
-            _make_conn()._validate_params({1, 2, 3})  # type: ignore[arg-type]
+            _make_conn()._validate_params({1, 2, 3})
 
     def test_rejects_frozenset(self) -> None:
         with pytest.raises(DataError, match="set"):
-            _make_conn()._validate_params(frozenset({1, 2, 3}))  # type: ignore[arg-type]
+            _make_conn()._validate_params(frozenset({1, 2, 3}))
 
     def test_str_and_bytes_still_rejected(self) -> None:
         with pytest.raises(DataError, match="str"):