fix: add media type for cmdline

Author: nkraetzschmar

src/gardenlinux/constants.py

@@ -83,6 +83,7 @@
     "squashfs",
     "manifest",
     "vmlinuz",
+    "cmdline",
     "release",
     "initrd",
     "tar.gz",
@@ -121,6 +122,7 @@
     "release": "application/io.gardenlinux.release",
     "vmlinuz": "application/io.gardenlinux.kernel",
     "initrd": "application/io.gardenlinux.initrd",
+    "cmdline": "application/io.gardenlinux.cmdline",
     "initrd.unified": "application/io.gardenlinux.initrd",
     "root.squashfs": "application/io.gardenlinux.squashfs",
     "squashfs": "application/io.gardenlinux.squashfs",