version.hpp: 0.15.1 (#1417)

Forgot to bump this for the release.
Will patch this in for package managers...

Author: ax3l

include/openPMD/version.hpp

@@ -29,7 +29,7 @@
  */
 #define OPENPMDAPI_VERSION_MAJOR 0
 #define OPENPMDAPI_VERSION_MINOR 15
-#define OPENPMDAPI_VERSION_PATCH 0
+#define OPENPMDAPI_VERSION_PATCH 1
 #define OPENPMDAPI_VERSION_LABEL ""
 /** @} */