build: Require Harfbuzz 0.9.29

There has been an API change in HB:

    -hb_ot_layout_language_get_required_feature_index
    +hb_ot_layout_language_get_required_feature

Commit: da132937989acb4d8ca9bd41c79f98750e7dda30

So we need to bump the dependency.
ot-info: Update after API break in HarfBuzz