Loosen the scipy condition in requirements.txt (quantumlib#6549)

In order to avoid the conflict of requirement specs for packages that need older scipy
just require that scipy is pinned to versions before 1.13.

For previous context for scipy ~=1.12 see quantumlib#6545 and quantumlib#6543

Author: BichengYing

cirq-core/requirements.txt

@@ -7,7 +7,7 @@ networkx>=2.4
 numpy~=1.16
 pandas
 sortedcontainers~=2.0
-scipy~=1.12.0
+scipy<1.13.0
 sympy
 typing_extensions>=4.2
 tqdm