configure.ac: post-release bump to 3.7.4
configure.ac: post-release bump to 3.7.4

pexip/pygobject,GNOME/pygobject,davibe/pygobject,GNOME/pygobject,davibe/pygobject,davibe/pygobject,sfeltman/pygobject,pexip/pygobject,sfeltman/pygobject,pexip/pygobject,davibe/pygobject,GNOME/pygobject,sfeltman/pygobject