fractal: 4.0.0 -> 4.2.0

Build system changes happening in the following commits:

* https://gitlab.gnome.org/GNOME/fractal/commit/79bf10af6ddecf50b0dc7641658694c196f73403
* https://gitlab.gnome.org/GNOME/fractal/commit/6982765607fb0a0c9e5eae4ad32659b29e5d0fb3
* https://gitlab.gnome.org/GNOME/fractal/commit/4abfa58282e958b2ab6fe44c5e3963d1b5db258a

Submitted MR upstream to update Cargo.lock [0] and to
make scripts executable [1].

[0]: https://gitlab.gnome.org/GNOME/fractal/merge_requests/446
[1]: https://gitlab.gnome.org/GNOME/fractal/merge_requests/447