Enable some stricter typing rules (#679)

Author: dstansby

numcodecs/checksum32.py

@@ -13,7 +13,7 @@
 
 _crc32c: Optional[ModuleType] = None
 with suppress(ImportError):
-    import crc32c as _crc32c  # type: ignore[no-redef]
+    import crc32c as _crc32c  # type: ignore[no-redef, unused-ignore]
 
 if TYPE_CHECKING:  # pragma: no cover
     from typing_extensions import Buffer

pyproject.toml

@@ -237,3 +237,6 @@ enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]
 # TODO: set options below to true
 strict = false
 warn_unreachable = false
+warn_redundant_casts = true
+warn_unused_ignores = true
+warn_unused_configs = true