Fix flakey tests

(cherry picked from commit a77778079b68682fa334314e7b38db80562270d0)

# Conflicts:
#	Sources/ComposableArchitecture/TestStore.swift

Author: stephencelis

Sources/ComposableArchitecture/TestStore.swift

@@ -269,6 +269,7 @@
 
           switch effects.operation {
           case .none:
+            self.effectDidSubscribe.continuation.yield()
             return .none
           case .producer, .run:
             let effect = LongLivingEffect(file: action.file, line: action.line)