feat(sdk): 添加大小写不敏感的 HTTP 响应头读取方法

Sources/DuooomiBleSDK/Utils/BeijingTimeProvider.swift

@@ -69,7 +69,7 @@ final class BeijingTimeProvider {
             }
 
             if let http = resp as? HTTPURLResponse,
-               let dateHeader = (http.allHeaderFields["Date"] ?? http.allHeaderFields["date"]) as? String,
+               let dateHeader = http.headerValue(caseInsensitive: "Date"),
                let value = self.formatHTTPDateHeader(dateHeader) {
                 done(value)
                 return