fix: test case for linux

Author: ensan-hcl

Core/Tests/CoreTests/UserDictionaryTests/UserDictionaryTests.swift

@@ -2,8 +2,14 @@
 import Testing
 
 @Test func testSystemUserDictionaryHelper() async throws {
+    #if os(macOS)
     let entries = try await SystemUserDictionaryHelper.fetchEntries()
     print(entries)
     // always true
     #expect(entries.count >= 0)
+    #else
+    #expect(throws: SystemUserDictionaryHelper.FetchError.unsupportedOperatingSystem) {
+        _ = try await SystemUserDictionaryHelper.fetchEntries()
+    }
+    #endif
 }