libportal: upgrade 0.9.0 -> 0.9.1

libportal: upgrade 0.9.0 -> 0.9.1

Changelog:
===========
- Meson 0.55.0 is required
- Fix memory management in the Input Capture portal code
- Correct the type used for GObject signal connections
- Remove wrong '(closure)' annotations, fixing GObject-Introspection warnings
- Don't require a C++ compiler for the build architecture
- Fix Meson warnings
- Consistently use '#pragma once'
- Initialize all g_autoptr variables

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>