Support Pydantic v2 (#364)

* Bump up mypy version to 1.0.1

* Import from Pydantic conditioned on whether it has `v1`

* Bump up Pydantic dev version to 2.3.0

fawltydeps/main.py

@@ -17,7 +17,10 @@
 from operator import attrgetter
 from typing import Dict, Iterator, List, Optional, Set, TextIO, Type
 
-from pydantic.json import custom_pydantic_encoder  # pylint: disable=no-name-in-module
+try:  # import from Pydantic V2
+    from pydantic.v1.json import custom_pydantic_encoder
+except ModuleNotFoundError:
+    from pydantic.json import custom_pydantic_encoder  # type: ignore[no-redef]
 
 from fawltydeps import extract_declared_dependencies, extract_imports
 from fawltydeps.check import calculate_undeclared, calculate_unused

fawltydeps/settings.py

@@ -8,9 +8,14 @@
 from pathlib import Path
 from typing import ClassVar, List, Optional, Set, TextIO, Tuple, Type, Union
 
-from pydantic import BaseSettings
-from pydantic.env_settings import SettingsSourceCallable  # pylint: disable=E0611
-from pydantic.json import custom_pydantic_encoder  # pylint: disable=no-name-in-module
+try:  # import from Pydantic V2
+    from pydantic.v1 import BaseSettings
+    from pydantic.v1.env_settings import SettingsSourceCallable
+    from pydantic.v1.json import custom_pydantic_encoder
+except ModuleNotFoundError:
+    from pydantic import BaseSettings  # type: ignore[no-redef]
+    from pydantic.env_settings import SettingsSourceCallable  # type: ignore[no-redef]
+    from pydantic.json import custom_pydantic_encoder  # type: ignore[no-redef]
 
 from fawltydeps.types import CustomMapping, ParserChoice, PathOrSpecial, TomlData
 
@@ -93,7 +98,7 @@ def parse_path_or_stdin(arg: str) -> PathOrSpecial:
     return Path(arg)
 
 
-class Settings(BaseSettings):  # type: ignore
+class Settings(BaseSettings):
     """FawltyDeps settings.
 
     Below, you find the defaults, these can be overridden in multiple ways: