increase size of murasoi:/boot

unattended-upgrade(8) caused murasoi:/boot to fill up around 2022-07-04 , and it will likely recur soon: https://discord.com/channels/264401248676085760/264401248676085760/993398521766105118

tpg: Random note to check tonight: Murasoi's / is aparently full

https://discord.com/channels/264401248676085760/671351866071842836/993281253375742004

> [6:25 AM] BOT Grafana: [Alerting] All File Systems, disk usage alert
> This file system has gone above 95% usage, perhaps it's worth a look...
> murasoi's ext4 /dev/mapper/murasoi-boot at /boot

• df(1)
• pvs(8)/vgs(8)/lvs(8)
• lvextend(8)/lvresize(8)

Probably still needs an occasional cosmetic:

• dpkg --purge $(dpkg -l '*4.19.0-17*'|awk '{print $2}'|grep linux)
• or DebianPkg:byobu's purge-old-kernels(1)