Convert SatsPrice to a Skip multiplatform app

Sources/SatsPrice/Network/PriceFetcher.swift

@@ -0,0 +1,15 @@
+// This is free software: you can redistribute and/or modify it
+// under the terms of the GNU General Public License 3.0
+// as published by the Free Software Foundation https://fsf.org
+//
+//  PriceFetcher.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/19/24.
+//
+
+import Foundation
+
+protocol PriceFetcher {
+    func btcToUsd() async throws -> Decimal?
+}