How to solve this dependency bug?

Question

I am trying to install google-cloud-sdk, but there is an exception:

(base) jinggu@jinggu-MS-7B79:~$ sudo apt-get install google-cloud-sdk
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
 google-cloud-sdk : Depends: python2.7 but it is not going to be installed
                    Recommends: python-crcmod but it is not going to be installed
 linux-image-generic-hwe-18.04 : Depends: linux-image-5.0.0-32-generic but it is not going to be installed
 linux-modules-extra-5.0.0-32-generic : Depends: linux-image-5.0.0-32-generic but it is not going to be installed or
                                                 linux-image-unsigned-5.0.0-32-generic but it is not going to be installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

I tried apt --fix-broken install but it still does not work.

A possible reason is that /boot partition is out of storage. What should I do with /boot? If directly deleting, which files should I delete? Here is the files in /boot

(base) jinggu@jinggu-MS-7B79:/boot$ ls
config-4.18.0-15-generic  grub                          lost+found      memtest86+_multiboot.bin      vmlinuz-4.18.0-15-generic
config-5.0.0-31-generic   initrd.img-4.18.0-15-generic  memtest86+.bin  System.map-4.18.0-15-generic  vmlinuz-5.0.0-31-generic
efi                       initrd.img-5.0.0-31-generic   memtest86+.elf  System.map-5.0.0-31-generic

Thanks for any suggestions.