CI: Fix python ty runs with latest ty beta

- Add missing cast
- Fix unnecessary cast in test_load_file.py

api/python/slint/build_docs.py

@@ -5,11 +5,13 @@ import slint
 import pdoc
 import pathlib
 import subprocess
+import typing
 
 
 doc = pdoc.doc.Module(slint)
 
-model_cls = doc.get("Model")
+model_cls = typing.cast(pdoc.doc.Class, doc.get("Model"))
+assert model_cls is not None
 for method in model_cls.inherited_members[("builtins", "PyModelBase")]:
     method.is_inherited = False
     if not method.name.startswith("_") and method.name != "init_self":

api/python/slint/tests/test_load_file.py

@@ -4,7 +4,6 @@
 import pytest
 from slint import load_file, CompileError
 from pathlib import Path
-import typing
 
 
 def base_dir() -> Path:
@@ -56,7 +55,7 @@ def test_load_file_fail() -> None:
 def test_compile_error() -> None:
     with pytest.raises(CompileError) as excinfo:
         load_file(base_dir() / "test-file-error.slint")
-    err = typing.cast(CompileError, excinfo.value)
+    err = excinfo.value
     diagnostics = err.diagnostics
     assert len(diagnostics) == 2
     assert diagnostics[0].message == "Unknown type 'garbage'"