Loosen networkx requirements (#6105)

* Update requirements.txt

* Update requirements.txt

* Update requirements.txt

* Update requirements.txt

Author: vtomole

cirq-core/requirements.txt

@@ -5,7 +5,7 @@ backports.cached_property~=1.0.1; python_version < '3.8'
 
 duet~=0.2.8
 matplotlib~=3.0
-networkx~=2.4
+networkx>=2.4
 numpy>=1.16,<1.24
 pandas
 sortedcontainers~=2.0