storage/curl: fix can't get timestamp of remote file

NEWS

 ver 0.23.10 (not yet released)
+* storage
+  - curl: fix file time stamps
 * decoder
   - ffmpeg: fix libfmt 9 compiler warning
 * encoder

src/storage/plugins/CurlStorage.cxx

@@ -284,6 +284,7 @@ public:
 				  "<a:resourcetype/>"
 				  "<a:getcontenttype/>"
 				  "<a:getcontentlength/>"
+				  "<a:getlastmodified/>"
 				  "</a:prop>"
 				  "</a:propfind>");
 	}