Allow store publisher to be used as async sequence. (#3763)

* Allow store publisher to be used as async sequence.

* Update StoreTests.swift

* Update publisher to use withState for currentState

---------

Co-authored-by: Stephen Celis <[email protected]>

Author: mbrandonw

Sources/ComposableArchitecture/Store.swift

@@ -1,4 +1,5 @@
 import Combine
+import CombineSchedulers
 import Foundation
 import SwiftUI
 
@@ -375,7 +376,7 @@ public final class Store<State, Action>: _Store {
   public var publisher: StorePublisher<State> {
     StorePublisher(
       store: self,
-      upstream: self.core.didSet.map { self.currentState }
+      upstream: self.core.didSet.receive(on: UIScheduler.shared).map { self.withState(\.self) }
     )
   }
 

Tests/ComposableArchitectureTests/StoreTests.swift

@@ -1175,6 +1175,14 @@ final class StoreTests: BaseTCATestCase {
     XCTAssertNil(weakStore)
   }
 
+  @MainActor
+  func testPublisherAsyncSequence() async {
+    if #available(iOS 15, macOS 12, tvOS 15, watchOS 8, *) {
+      let store = Store<Void, Void>(initialState: ()) {}
+      _ = await store.publisher.values.first { @Sendable _ in true }
+    }
+  }
+
   @MainActor
   func testSharedMutation() async {
     XCTTODO(