Update base image to nginx:1.25.3-bookworm

[itskingori]

Updating the version because there's a new version and moving off Alpine because the single-request-reopen option we use in resolve.conf has no effect on Alpine containers. Their resolver only supports ndots, attempts, and timeout. As much as the DNS issues have been addressed with the upgrade in #10, I think we should just move off Alpine and not have to worry about anything.

References

• https://git.musl-libc.org/cgit/musl/tree/src/network/resolvconf.c#n40
• https://blog.quentin-machu.fr/2018/06/24/5-15s-dns-lookups-on-kubernetes/