Add support for Plasma6

[zupo]

To do this we have to update to latest nixpkgs. But, Plasma5 was dropped from latest nixpkgs, so we have to:

• [screenlock] add a test for Plasma6
• [screenlock] rewrite the setup for the test for Plasma5
• [autologin] rewrite to use Plasma 6

I also removed some GNOME deprecation warnings.

[github-actions]

Merging this branch will decrease overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/ParetoSecurity/agent/checks/linux	89.61% (-0.14%)	👎
Total	46.46%

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/ParetoSecurity/agent/checks/linux/password_unlock.go	89.83% (-1.40%)	59 (+2)	53 (+1)	6 (+1)	👎

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

[zupo]

@am-on: I managed to fix a bunch of failing tests, but I don't understand why minimal in trayicon.nix would be failing here and passing in main. Could you please have a look?

$ nix build .#checks.x86_64-linux.trayicon
error: builder for '/nix/store/0jyrkrz93qsb5iz1df8k4jfl1rblphz2-vm-test-run-Trayicon.drv' failed with exit code 1;
       last 25 log lines:
       > minimal # [   10.738367] su[1132]: pam_unix(su:session): session opened for user alice(uid=1000) by (uid=0)
       > minimal # [   10.750451] su[1132]: pam_unix(su:session): session closed for user alice
       > !!! Test "Minimal desktop environment failure handling" failed with error: "Expected error message not found in output:   ⨯ An instance of ParetoSecurity tray application is already running. error=resource temporarily unavailable
       > "
       > cleanup
       > kill machine (pid 46)
       > qemu-system-x86_64: terminating on signal 15 from pid 8 (/nix/store/829wb290i87wngxlh404klwxql5v18p4-python3-3.13.7/bin/python3.13)
       > kill vlan (pid 9)
       > (finished: cleanup, in 0.01 seconds)
       > Traceback (most recent call last):
       >   File "/nix/store/faamqzi4l9cwhqkkk833vayxf0sn4q34-nixos-test-driver-1.1/bin/.nixos-test-driver-wrapped", line 9, in <module>
       >     sys.exit(main())
       >              ~~~~^^
       >   File "/nix/store/faamqzi4l9cwhqkkk833vayxf0sn4q34-nixos-test-driver-1.1/lib/python3.13/site-packages/test_driver/__init__.py", line 162, in main
       >     driver.run_tests()
       >     ~~~~~~~~~~~~~~~~^^
       >   File "/nix/store/faamqzi4l9cwhqkkk833vayxf0sn4q34-nixos-test-driver-1.1/lib/python3.13/site-packages/test_driver/driver.py", line 246, in run_tests
       >     self.test_script()
       >     ~~~~~~~~~~~~~~~~^^
       >   File "/nix/store/faamqzi4l9cwhqkkk833vayxf0sn4q34-nixos-test-driver-1.1/lib/python3.13/site-packages/test_driver/driver.py", line 204, in test_script
       >     exec(self.tests, symbols, None)
       >     ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
       >   File "<string>", line 26, in <module>
       > AssertionError: Expected error message not found in output:   ⨯ An instance of ParetoSecurity tray application is already running. error=resource temporarily unavailable
       > 

[zupo]

This sadly needs to be a separate file to get the old 24.11 nixpkgs in there.

If someone can figure out how to merge this into screenlock.nix, I'm all ears!