And don't build Fedora 28 by default. It's aleady end of life.
But for now keep it, so it can be triggered manually.

Fedora 32 drops "python" from the path. Hence "/usr/bin/env python" won't
work anymore. Of course, who needs a way to invoke the interpreter that works
accross different distributions! WTF.

In this case, easy to work around. We run it from meson, so we have access to the Python 3
binary. Just call it directly like we do for autotools.

"wireless-tools-devel" is long depreacted and not used by
NetworkManager, not even for WEXT.

Drop it from the build dependencies.

REQUIRED_PACKAGES has two uses:

 - to setup a system for developing NetworkManager. This installs
   convenience packages like "cscope".

 - to install the packages required for unit testing in gitlab-ci.

For gitlab-ci we should only install the packages that we actually
need.

Previously, dnf/yum used to ignore packages that didn't exist.
In Fedora 32, dnf starts to fail the entire command:

  No match for argument: python-gobject-base
  Error: Unable to find a match: python-gobject-base

Since this script is supposed to work with different RHEL/Fedora
versions, it's expected that not all packages are available everywhere.

Fix that, by installing packages that we know that they might be missing
one by one (and ignore the error).

Python 3 doesn't like this:

    ======================================================================
    ERROR: test_001 (__main__.TestNmcli)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "./clients/tests/test-client.py", line 785, in f
        self._nm_test_post()
      File "./clients/tests/test-client.py", line 767, in _nm_test_post
        content_new = ''.join([r['content'] for r in results])
    TypeError: sequence item 0: expected str instance, bytes found

Recent Python versions warn about this:

  ./clients/tests/test-client.py:569: SyntaxWarning: "is" with a literal. Did you mean "=="?
    elif lang is de:
  ./clients/tests/test-client.py:572: SyntaxWarning: "is" with a literal. Did you mean "=="?
    elif lang is pl:

And rightly so: https://bugs.python.org/issue34850

test_001 (__main__.TestNmcli) ... /tmp/NetworkManager/tools/test-networkmanager-service.py:2346: PyGIDeprecationWarning: add_watch is deprecated; use GLib.io_add_watch() instead
  id1 = GLib.IOChannel(0).add_watch(GLib.IOCondition.HUP,

property_to_dbus() returns NULL when called with
NM_CONNECTION_SERIALIZE_WITH_SECRETS_AGENT_OWNED and the property is
not an agent-owned secrets. The function doesn't handle VPN secrets
correctly, since they are all stored as a hash in the vpn.secrets
property and the flag for each of them is a matching '*-flags' key in
the vpn.data property. VPN secrets must be handled differently; do it
in the VPN setting to_dbus_fcn() function.

Fixes: 71928a3e5cab ('settings: avoid cloning the connection to maintain agent-owned secrets')

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/230
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/merge_requests/280