Log Message:
gobject-introspection: update to 1.64.1.

1.64.1 - 2020-04-05
-------------------

* Replace calls to deprecated xml.etree.cElementTree removed in Python 3.9 \ 
:mr:`202` (:user:`Stephen Gallagher <sgallagher>`)
* gimarshallingtests: Use g_assert_cmpfloat_with_epsilon. Fixes tests on some \ 
architectures :mr:`200` (:user:`Iain Lane <iainl>`)