server: header: use lowercase header for chunked transfer encoding
#define MK_HEADER_CONN_UPGRADE "Connection: Upgrade" MK_CRLF
#define MK_HEADER_CONTENT_LENGTH "Content-Length: "
#define MK_HEADER_CONTENT_ENCODING "Content-Encoding: "
-#define MK_HEADER_TE_CHUNKED "Transfer-Encoding: Chunked" MK_CRLF
+#define MK_HEADER_TE_CHUNKED "Transfer-Encoding: chunked" MK_CRLF
#define MK_HEADER_LAST_MODIFIED "Last-Modified: "
#define MK_HEADER_UPGRADE_H2C "Upgrade: h2c" MK_CRLF
