bump product version to 7.3.1.0.0+

Change-Id: If592010b0b2c64b8a1999c1a6b4744e1d477491b
diff --git a/configure.ac b/configure.ac
index ce82177..5e3a1fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@ dnl in order to create a configure script.
# several non-alphanumeric characters, those are split off and used only for the
# ABOUTBOXPRODUCTVERSIONSUFFIX in openoffice.lst. Why that is necessary, no idea.

AC_INIT([LibreOffice],[7.3.0.1.0+],[],[],[http://documentfoundation.org/])
AC_INIT([LibreOffice],[7.3.1.0.0+],[],[],[http://documentfoundation.org/])

dnl libnumbertext needs autoconf 2.68, but that can pick up autoconf268 just fine if it is installed
dnl whereas aclocal (as run by autogen.sh) insists on using autoconf and fails hard