Fix nightly CI

Author: FranzBusch

Sources/_AsyncMergeSequence/Locking.swift

@@ -24,11 +24,11 @@
 //===----------------------------------------------------------------------===//
 
 #if canImport(Darwin)
-@_implementationOnly import Darwin
+import Darwin
 #elseif canImport(Glibc)
-@_implementationOnly import Glibc
+import Glibc
 #elseif canImport(WinSDK)
-@_implementationOnly import WinSDK
+import WinSDK
 #endif
 
 internal struct Lock {

Sources/_AsyncMergeSequence/Merge/AsyncMerge2Sequence.swift

@@ -23,7 +23,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-@_implementationOnly import DequeModule
+import DequeModule
 
 /// Creates an asynchronous sequence of elements from two underlying asynchronous sequences
 public func merge<Base1: AsyncSequence, Base2: AsyncSequence>(_ base1: Base1, _ base2: Base2) -> AsyncMerge2Sequence<Base1, Base2>

Sources/_AsyncMergeSequence/Merge/MergeStateMachine.swift

@@ -23,7 +23,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-@_implementationOnly import DequeModule
+import DequeModule
 
 /// The state machine for any of the `merge` operator.
 ///