Fix mypy error: Module "ray" does not explicitly export attribute "re…

…mote" (ray-project#36334)

ray-project#34730 changed `__all__` in `__init__.py` to a computed list. mypy doesn't support this. Reverting it back to a literal list to fix this issue.

Repro:
`mypy --strict --follow-imports=skip --ignore-missing-imports 1.py`

```python
# 1.py
import ray

@ray.remote
def foo() -> None:
    pass
```

Note, the reason why CI didn't catch this issue is because we don't enable strict mode, see [here](https://github.com/ray-project/ray/blob/407062499038344b0f3edb54b2c7985c3320d1ec/ci/lint/format.sh#L135). Currently we have too many issues if enabling strict mode. 

Signed-off-by: Hao Chen <[email protected]>

python/ray/__init__.py

@@ -183,7 +183,8 @@ def __getattr__(self, attr):
 state = _DeprecationWrapper("state", ray._private.state)
 
 
-RAY_APIS = {
+# Pulic Ray APIs
+__all__ = [
  "__version__",
  "_config",
  "get_runtime_context",
@@ -214,7 +215,7 @@ def __getattr__(self, attr):
  "LOCAL_MODE",
  "SCRIPT_MODE",
  "WORKER_MODE",
-}
+]
 
 # Public APIs that should automatically trigger ray.init().
 AUTO_INIT_APIS = {
@@ -254,15 +255,12 @@ def __getattr__(self, attr):
  "timeline",
 }
 
-assert RAY_APIS == AUTO_INIT_APIS | NON_AUTO_INIT_APIS
+assert set(__all__) == AUTO_INIT_APIS | NON_AUTO_INIT_APIS
 from ray._private.auto_init_hook import wrap_auto_init_for_all_apis # noqa: E402
 
 wrap_auto_init_for_all_apis(AUTO_INIT_APIS)
 del wrap_auto_init_for_all_apis
 
-
-__all__ = list(RAY_APIS)
-
 # Subpackages
 __all__ += [
  "actor",