ci: migrate to uv! (#4698)

* Migrate to `uv`
* Format `pyproject.toml` files properly
* Remove upper bounds on dependencies, and bounds on dev dependencies
(we should be using latest)
* Move to hatch for packaing

In the future we should:
* Set up dependabot / automate lockfile updates and tests
* Add tests for min compatible versions (I'll do this right after merge)
* Use dynamic versioning
* Bump `pydantic` to v2.11.4 in the lockfile, we have some tests failing

libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/__init__.py

@@ -1,8 +1,9 @@
 import random
 import sqlite3
 import threading
+from collections.abc import AsyncIterator, Iterator, Sequence
 from contextlib import closing, contextmanager
-from typing import Any, AsyncIterator, Dict, Iterator, Optional, Sequence, Tuple
+from typing import Any, Optional, cast
 
 from langchain_core.runnables import RunnableConfig
 
@@ -261,7 +262,12 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                 return CheckpointTuple(
                     config,
                     self.serde.loads_typed((type, checkpoint)),
-                    self.jsonplus_serde.loads(metadata) if metadata is not None else {},
+                    cast(
+                        CheckpointMetadata,
+                        self.jsonplus_serde.loads(metadata)
+                        if metadata is not None
+                        else {},
+                    ),
                     (
                         {
                             "configurable": {
@@ -283,7 +289,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
         self,
         config: Optional[RunnableConfig],
         *,
-        filter: Optional[Dict[str, Any]] = None,
+        filter: Optional[dict[str, Any]] = None,
         before: Optional[RunnableConfig] = None,
         limit: Optional[int] = None,
     ) -> Iterator[CheckpointTuple]:
@@ -349,7 +355,12 @@ class SqliteSaver(BaseCheckpointSaver[str]):
                         }
                     },
                     self.serde.loads_typed((type, checkpoint)),
-                    self.jsonplus_serde.loads(metadata) if metadata is not None else {},
+                    cast(
+                        CheckpointMetadata,
+                        self.jsonplus_serde.loads(metadata)
+                        if metadata is not None
+                        else {},
+                    ),
                     (
                         {
                             "configurable": {
@@ -428,7 +439,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
     def put_writes(
         self,
         config: RunnableConfig,
-        writes: Sequence[Tuple[str, Any]],
+        writes: Sequence[tuple[str, Any]],
         task_id: str,
         task_path: str = "",
     ) -> None:
@@ -496,7 +507,7 @@ class SqliteSaver(BaseCheckpointSaver[str]):
         self,
         config: Optional[RunnableConfig],
         *,
-        filter: Optional[Dict[str, Any]] = None,
+        filter: Optional[dict[str, Any]] = None,
         before: Optional[RunnableConfig] = None,
         limit: Optional[int] = None,
     ) -> AsyncIterator[CheckpointTuple]: