Use stricter mypy rules. exclude v1

Signed-off-by: Yurii Serhiichuk <savik.ne@gmail.com>

Author: xSAVIKx

mypy.ini

@@ -1,15 +1,20 @@
 [mypy]
-python_version = 3.8
+python_version = 3.9
 
+ignore_missing_imports = True
+namespace_packages = True
+explicit_package_bases = True
+scripts_are_modules = True
 pretty = True
 show_error_context = True
 follow_imports_for_stubs  = True
+warn_redundant_casts = True
+warn_unused_ignores = True
 # subset of mypy --strict
 # https://mypy.readthedocs.io/en/stable/config_file.html
 check_untyped_defs = True
 disallow_incomplete_defs = True
 warn_return_any = True
 strict_equality = True
-
-[mypy-deprecation.*]
-ignore_missing_imports = True
+disallow_untyped_defs = True
+exclude = src/cloudevents/v1