Fix protobuf version specifiers in cirq-google/requirements.txt (quantumlib#5408)

maffoo · augustehirth · commit 4126395b2f38 · 2022-05-27T14:16:20.000-07:00
diff --git a/cirq-google/requirements.txt b/cirq-google/requirements.txt
@@ -1,3 +1,3 @@
 google-api-core[grpc] >= 1.14.0, < 2.0.0dev
-proto-plus>=1.20.0
-protobuf>=3.13.0<4
+proto-plus >= 1.20.0
+protobuf >= 3.13.0, < 4
