Remove the pin for shiboken6

[almet]

Shiboken6 issued version 6.8.1.1 in last december. This version was released only for macOS, as as such makes poetry fail to work on other OSes.

We've pinned this version for our 0.8.1 release and now back-ported the changes on the main branch:

dangerzone/pyproject.toml

Lines 28 to 32 in b2f4e2d

	shiboken6 = [
	{version = "*", platform = "darwin"},
	{version = "<6.8.1.1", platform = "linux"},
	{version = "<6.8.1.1", platform = "win32"},
	]

Fedora is the only distro we know that issued a release for this 6.8.1.1 version. The .spec file for Fedora packaging replaces the information in pyproject.toml by any version:

dangerzone/install/linux/dangerzone.spec

Lines 229 to 233 in b2f4e2d

	# Bypass the version pin for Fedora as the 6.8.1.1 package is causing trouble
	# A 6.8.1.1 package was only released with a wheel for macOS, but was picked by
	# Fedora packagers. We cannot use "*" when PyPI is involved as it will fail to download the latest version.
	# For Fedora, we can pick any of the released versions.
	sed -i '/shiboken6 = \[/,/\]/c\shiboken6 = "*"' pyproject.toml

Once a new version of shiboken is out we should remove these: https://pypi.org/project/shiboken6/#history