Version bump.

src/core/nginx.h

diff --git a/src/core/nginx.h b/src/core/nginx.h
index ecdba25..9f66765 100644
--- a/src/core/nginx.h
+++ b/src/core/nginx.h
@@ -9,8 +9,8 @@
 #define _NGINX_H_INCLUDED_
 
 
-#define nginx_version      1015003
-#define NGINX_VERSION      "1.15.3"
+#define nginx_version      1015004
+#define NGINX_VERSION      "1.15.4"
 #define NGINX_VER          "nginx/" NGINX_VERSION
 
 #ifdef NGX_BUILD