docs/types: address review nits on ExecutionSourceContext

- drop the old-impl reference (env var) from the docstring
- use modern typing hints (str | None, Token[str | None] | None)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Valentina Bojan

packages/uipath-platform/src/uipath/platform/common/_execution_context.py

@@ -1,10 +1,9 @@
 from contextvars import ContextVar, Token
 from os import environ as env
-from typing import Optional
 
 from uipath.platform.common.constants import ENV_JOB_ID, ENV_JOB_KEY, ENV_ROBOT_KEY
 
-_execution_source: ContextVar[Optional[str]] = ContextVar(
+_execution_source: ContextVar[str | None] = ContextVar(
     "execution_source", default=None
 )
 
@@ -13,15 +12,15 @@ class ExecutionSourceContext:
     """Scope the execution source for the duration of a run.
 
     Carries the source (e.g. ``runtime``/``playground``/``eval``) via a context
-    variable instead of a process-global env var, and releases it on exit so it
-    stays correctly scoped in concurrent runs. The CLI enters this with
-    ``UiPathRuntimeContext.execution_source`` so platform clients can read it
-    via :attr:`UiPathExecutionContext.execution_source`.
+    variable and releases it on exit so it stays correctly scoped in concurrent
+    runs. The CLI enters this with ``UiPathRuntimeContext.execution_source`` so
+    platform clients can read it via
+    :attr:`UiPathExecutionContext.execution_source`.
     """
 
-    def __init__(self, execution_source: Optional[str]) -> None:
+    def __init__(self, execution_source: str | None) -> None:
         self._execution_source = execution_source
-        self._token: Optional[Token[Optional[str]]] = None
+        self._token: Token[str | None] | None = None
 
     def __enter__(self) -> "ExecutionSourceContext":
         self._token = _execution_source.set(self._execution_source)