Fix FTBFS with glib2 2.77 (rhbz#2226033}
    
    glib2 2.77.0 changed the formatting of keyfiles, and 2.77.1 fixed only
    some aspects. notmuch tests for the exact output, though.
    
    As a hotfix, adjust the expected output of the relevant test to the
    output with glib2 2.77.1 for Fedora 39+.
    
    A real fix will consist of changes both to glib2 (write file comments
    again) and notmuch (do not check for empty lines).