Usage of GET requests for checking updates was made deprecated
at website some time ago [1], but REST endpoint was
CSRF-protected until recently [2].
The body of update request may be big enough and thus does not
suitable for GET requests.
[1] 0b38da1b2b
[2] e3ab0c07dc
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1781>