Update version to 0.19.3

[eeeebbbbrrrr]

Welcome to pgrx v0.19.3! This includes support for Postgres 19beta4, some cargo-pgrx CLI improvements, many more (all!) Postgres headers, and a few bugfixes and cleanups.

As always, please install cargo-pgrx with cargo install cargo-pgrx --version 0.19.3 --locked.

Thank you to the new contributors and to the regulars, too! Your work is appreciated.

What's Changed

We have Postgres 19beta4 support as of #2383.

More (all!) Postgres Headers

• include more headers by @usamoi in include more headers #2377

This PR gives us a script to update the various pgXX.h header files straight from the Postgres sources and now essentially all headers are included. Thanks @usamoi!

cargo-pgrx improvements

• Add --cargo passthrough support for cargo commands by @isdaniel in Add --cargo passthrough support for cargo commands #2343
• add --prefix option to package command by @AndrewJackson2020 in add prefix option to package command #2382

Cleanups

• fix: reduce the amount of useless allocations for errors on hot paths by @Ddystopia in fix: reduce the amount of useless allocations for errors on hot paths #2369
• Use path-lookup of pgrx modules in shmem macros by @cbandy in Use path-lookup of pgrx modules in shmem macros #2371

Correctness/Safety

• hold interrupts before calling do_report if level != ERROR by @usamoi in hold interrupts before calling do_report if level != ERROR #2374
• Avoid unsafe intermediate slice construction in varlena functions by @SergeiPatiakin in Avoid unsafe intermediate slice construction in varlena functions #2368

Misc

• Add AGENTS.md with Rust safety and contribution rules by @eeeebbbbrrrr in Add AGENTS.md with Rust safety and contribution rules #2384
• Update cargo-pgrx skill for current commands and private worktrees by @eeeebbbbrrrr in Update cargo-pgrx skill for current commands and private worktrees #2385

New Contributors

• @Ddystopia made their first contribution in fix: reduce the amount of useless allocations for errors on hot paths #2369
• @AndrewJackson2020 made their first contribution in add prefix option to package command #2382

Full Changelog: v0.19.2...v0.19.3