Fix tests compilation for Swift 5.8-5.10 on Linux

Author: Frizlab

Tests/JSONLoggerTests.swift

@@ -12,13 +12,17 @@ final class JSONLoggerTests : XCTestCase {
 	public static let defaultJSONDecoder: JSONDecoder = {
 		let res = JSONDecoder()
 		if #available(macOS 12.0, tvOS 15.0, iOS 15.0, watchOS 8.0, *) {
+#if canImport(Darwin) || compiler(>=6)
 			res.allowsJSON5 = false
+#endif
 		}
 		res.keyDecodingStrategy = .useDefaultKeys
 		res.dateDecodingStrategy = .iso8601
 		res.dataDecodingStrategy = .base64
 		if #available(macOS 12.0, tvOS 15.0, iOS 15.0, watchOS 8.0, *) {
+#if canImport(Darwin) || compiler(>=6)
 			res.assumesTopLevelDictionary = false
+#endif
 		}
 		res.nonConformingFloatDecodingStrategy = .throw
 		return res