Check version number consistency on updates

[mhvk]

When we moved to meson for building by default, we updated the release instructions to change version numbers in meson.build. But we still also have to make changes in configure.ac, since that way of building is also supported, and in fact is what is used by pyerfa.

I now updated the release instructions to reflect this, but, really, it would be nicer if there was just one place!

Any ideas?

p.s. If not, we probably should at least have a CI run that checks that everything is consistent.

[rmathar]

If one is able to run something beyond the standard meson command, one can extract the number from configure.ac

VERSION=$(grep AC_INIT configure.ac | tr "(,][" "   " | awk '{print $3}')
meson rewrite kwargs set project / version $VERSION

but this is insufficient because the 8-digit SOFA_VERSION also needs to be copied to match the AC_DEFINE in configure.ac.