Fix #1249

Author: yhirose

httplib.h

@@ -12,6 +12,10 @@
  * Configuration
  */
 
+#define CPPHTTPLIB_VERSION_MAJOR 0
+#define CPPHTTPLIB_VERSION_MINOR 10
+#define CPPHTTPLIB_VERSION_PATCH 4
+
 #ifndef CPPHTTPLIB_KEEPALIVE_TIMEOUT_SECOND
 #define CPPHTTPLIB_KEEPALIVE_TIMEOUT_SECOND 5
 #endif
@@ -6194,7 +6198,11 @@ inline bool ClientImpl::write_request(Stream &strm, Request &req,
 
 #ifndef CPPHTTPLIB_NO_DEFAULT_USER_AGENT
   if (!req.has_header("User-Agent")) {
-    req.headers.emplace("User-Agent", "cpp-httplib/0.10.4");
+    auto agent = "cpp-httplib/" +
+                        std::to_string(CPPHTTPLIB_VERSION_MAJOR) + "." +
+                        std::to_string(CPPHTTPLIB_VERSION_MINOR) + "." +
+                        std::to_string(CPPHTTPLIB_VERSION_PATCH);
+    req.headers.emplace("User-Agent", agent);
   }
 #endif