fix: use Union[] syntax for Python < 3.10 compatibility

Replace `float | Tuple[float, float]` union type annotation with
`Union[float, Tuple[float, float]]` in StarmapSession.__init__ to
maintain compatibility with Python versions older than 3.10, which
do not support the PEP 604 `X | Y` syntax at runtime.

Refers to SPSTRAT-731

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: JAVGan

starmap_client/session.py

@@ -36,7 +36,7 @@ def __init__(
         api_version: str,
         retries: int = 3,
         backoff_factor: float = 2.0,
-        timeout: float | Tuple[float, float] = 10.0,
+        timeout: Union[float, Tuple[float, float]] = 10.0,
     ):
         """
         Create the StarmapSession object.