fix: Makes TokenInitPayload init public

Author: NeedleInAJayStack

Sources/GraphQLWS/InitPayloads.swift

@@ -5,5 +5,9 @@ public struct EmptyInitPayload: Equatable & Codable { }
 
 /// `connection_init` `payload` that includes an `authToken` field
 public struct TokenInitPayload: Equatable & Codable {
-    let authToken: String
+    public let authToken: String
+    
+    public init(authToken: String) {
+        self.authToken = authToken
+    }
 }