update pocketbase hosted on fly.io

• Check latest release e.g. 0.17.5
• cd /path/to/pocketbase-on-fly
• nano Dockerfile
• Update ARG PB_VERSION e.g. ARG PB_VERSION=0.17.5
• Save and exit
• flyctl deploy

References

• Upgrade your version of pocketbase in local server and live on fly.io app