mkosi: Update to latest

- Drop Netdev= as it was removed in mkosi
- Always install python-psutil in the final image (required for networkd tests)
- Always Install python-pytest in the final image (required for ukify tests)
- Use the narrow glob for all centos python packages
- Drop the networkd mkosi config files (the default image can be used instead)
- Use ".conf" as the mkosi config file suffix everywhere
- Copy src/ to /root/src in the final image and set gdb substitute path in
  .gdbinit to make gdb work properly

.github/workflows/mkosi.yml

@@ -1,7 +1,7 @@
 ---
 # vi: ts=2 sw=2 et:
 # SPDX-License-Identifier: LGPL-2.1-or-later
-# Simple boot tests that build and boot the mkosi images generated by the mkosi config files in mkosi.default.d/.
+# Simple boot tests that build and boot the mkosi images generated by the mkosi config files in mkosi.conf.d/.
 name: mkosi
 
 on:
@@ -73,11 +73,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c
-    - uses: systemd/mkosi@36638fb37e0ccbb97bbaa573d158dcea3a5f9bde
+    - uses: systemd/mkosi@af1fe54805c84bb09e80bb585399121946fec701
 
     - name: Configure
       run: |
-        tee mkosi.default <<- EOF
+        tee mkosi.conf <<- EOF
         [Distribution]
         Distribution=${{ matrix.distro }}
         Release=${{ matrix.release }}