Bump version numbers

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/include/mbedtls/version.h b/include/mbedtls/version.h
index 0ef5213..1ae06e6 100644
--- a/include/mbedtls/version.h
+++ b/include/mbedtls/version.h
@@ -38,16 +38,16 @@
  */
 #define MBEDTLS_VERSION_MAJOR  2
 #define MBEDTLS_VERSION_MINOR  28
-#define MBEDTLS_VERSION_PATCH  3
+#define MBEDTLS_VERSION_PATCH  4
 
 /**
  * The single version number has the following structure:
  *    MMNNPP00
  *    Major version | Minor version | Patch version
  */
-#define MBEDTLS_VERSION_NUMBER         0x021C0300
-#define MBEDTLS_VERSION_STRING         "2.28.3"
-#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.28.3"
+#define MBEDTLS_VERSION_NUMBER         0x021C0400
+#define MBEDTLS_VERSION_STRING         "2.28.4"
+#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.28.4"
 
 #if defined(MBEDTLS_VERSION_C)