Increase version to 2.5.3.

VERSION.cmake

@@ -1,6 +1,6 @@
 set( MIRALL_VERSION_MAJOR 2 )
 set( MIRALL_VERSION_MINOR 5 )
-set( MIRALL_VERSION_PATCH 2 )
+set( MIRALL_VERSION_PATCH 3 )
 set( MIRALL_VERSION_YEAR  2019 )
 set( MIRALL_SOVERSION 0 )