Bump version to 1.2.0 for release

Author: ldionne

include/boost/hana/version.hpp

@@ -24,7 +24,7 @@ Distributed under the Boost Software License, Version 1.0.
 
 //! @ingroup group-config
 //! Macro expanding to the minor version of the library, i.e. the `y` in `x.y.z`.
-#define BOOST_HANA_MINOR_VERSION 1
+#define BOOST_HANA_MINOR_VERSION 2
 
 //! @ingroup group-config
 //! Macro expanding to the patch level of the library, i.e. the `z` in `x.y.z`.