fix: MacのサポートOSを10.15に変更

SNQ-2001 · SNQ-2001 · commit 5a87c1afac5f · 2023-03-07T14:13:54.000+09:00
diff --git a/Package.swift b/Package.swift
@@ -7,7 +7,7 @@ let package = Package(
     name: "AppVersionMonitorSwiftUI",
     platforms: [
         .iOS(.v13),
-        .macOS(.v10_13),
+        .macOS(.v10_15),
         .tvOS(.v11),
         .watchOS(.v5)
     ],
