Upgrade to pydantic 2.

* Update dependencies
* Run `bump-pydantic` to migrate some code: https://docs.pydantic.dev/latest/migration/
* Adapt the toml parsing per pydantic/pydantic#2335

requirements/prod.txt

@@ -1,5 +1,6 @@
 astral==3.2
 pillow==10.2.0
-pydantic==1.10.14
+pydantic==2.6.0
+pydantic-settings==2.1.0
 python-dotenv==1.0.1
 requests==2.31.0

wspp/settings.py

@@ -1,38 +1,50 @@
 import tomllib
 from pathlib import Path
+from typing import Any
 
-from pydantic import BaseModel, BaseSettings, DirectoryPath, PositiveInt, confloat
-from pydantic.env_settings import EnvSettingsSource
-from pydantic.utils import deep_update
+from pydantic import BaseModel, DirectoryPath, Field, PositiveInt
+from pydantic.fields import FieldInfo
+from pydantic_settings import (
+    BaseSettings,
+    EnvSettingsSource,
+    PydanticBaseSettingsSource,
+)
+from typing_extensions import Annotated
 
 from wspp import slack, weatherstack
 
 
 class WsppSettings(BaseModel):
-    latitude: confloat(ge=-90.0, le=90.0)
-    longitude: confloat(ge=-180.0, le=180.0)
+    latitude: Annotated[float, Field(ge=-90.0, le=90.0)]
+    longitude: Annotated[float, Field(ge=-180.0, le=180.0)]
     profile_photos_dir: DirectoryPath = Path(__file__).parent.parent / "profile_photos"
     polling_interval_s: PositiveInt = 7200
 
 
+# https://github.com/pydantic/pydantic/issues/2335
+class TOMLConfigSettingsSource(PydanticBaseSettingsSource):
+    def get_field_value(
+        self, field: FieldInfo, field_name: str
+    ) -> tuple[Any, str, bool]:
+        return super().get_field_value(field, field_name)
+
+    def __call__(self) -> dict[str, Any]:
+        return tomllib.loads(Path("config.toml").read_text())
+
+
 class Settings(BaseSettings):
     wspp: WsppSettings
     weatherstack: weatherstack.WeatherstackSettings
     slack: list[slack.SlackSettings]
 
     @classmethod
-    def read(cls):
-        # Pydantic doesn't have built-in support for toml files, so we
-        # have to load the toml file (and override with any env vars)
-        # ourselves.
-        # https://github.com/pydantic/pydantic/issues/2335
-        toml_settings = Settings(**tomllib.loads(Path("config.toml").read_text()))
-        env_data = EnvSettingsSource(
-            env_file=None,
-            env_file_encoding=None,
-            env_nested_delimiter="__",
-        )(toml_settings)
-        return Settings.parse_obj(obj=deep_update(toml_settings.dict(), env_data))
-
-
-settings = Settings.read()
+    def settings_customise_sources(
+        cls, *_args, **_kwargs
+    ) -> tuple[PydanticBaseSettingsSource, ...]:
+        return (
+            EnvSettingsSource(Settings, env_nested_delimiter="__"),
+            TOMLConfigSettingsSource(Settings),
+        )
+
+
+settings = Settings()