我该如何解决这个警告？
addgroup: The group `input' already exists as a system group. Exiting.
update-initramfs: deferring update (trigger activated)
Setting up grub-common (2.02~beta2-36ubuntu3.21) ...
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
Setting up grub2-common (2.02~beta2-36ubuntu3.21) ...
Setting up grub-efi-amd64-bin (2.02~beta2-36ubuntu3.21) ...
Setting up grub-efi-amd64 (2.02~beta2-36ubuntu3.21) ...
Installing for x86_64-efi platform.
Installation finished. No error reported.
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported. …$ sudo apt-get install
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-4.15.0-29 linux-headers-4.15.0-29-generic
linux-image-4.15.0-29-generic linux-modules-4.15.0-29-generic
linux-modules-extra-4.15.0-29-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 7 not upgraded.
~$ sudo apt autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
linux-headers-4.15.0-29 linux-headers-4.15.0-29-generic
linux-image-4.15.0-29-generic linux-modules-4.15.0-29-generic
linux-modules-extra-4.15.0-29-generic
0 upgraded, 0 newly …