doc: bump boost version in release-process

This was forgotten in bitcoin#3501.

doc/release-process.md

@@ -45,7 +45,7 @@ Release Process
 	wget 'http://zlib.net/zlib-1.2.8.tar.gz'
 	wget 'ftp://ftp.simplesystems.org/pub/png/src/libpng16/libpng-1.6.8.tar.gz'
 	wget 'https://fukuchi.org/works/qrencode/qrencode-3.4.3.tar.bz2'
-	wget 'https://downloads.sourceforge.net/project/boost/boost/1.54.0/boost_1_54_0.tar.bz2'
+	wget 'https://downloads.sourceforge.net/project/boost/boost/1.55.0/boost_1_55_0.tar.bz2'
 	wget 'https://svn.boost.org/trac/boost/raw-attachment/ticket/7262/boost-mingw.patch' -O \ 
 	     boost-mingw-gas-cross-compile-2013-03-03.patch
 	wget 'https://download.qt-project.org/official_releases/qt/5.2/5.2.0/single/qt-everywhere-opensource-src-5.2.0.tar.gz'