## Problem
Current compute images for Postgres 14-16 don't build on Debian 12
because of issues with extensions.
This PR fixes that, but for the current setup, it is mostly a no-op
change.
## Summary of changes
- Use `/bin/bash -euo pipefail` as SHELL to fail earlier
- Fix `plv8` build: backport a trivial patch for v8
- Fix `postgis` build: depend `sfgal` version on Debian version instead
of Postgres version
Tested in: https://github.com/neondatabase/neon/pull/9849
