Bumps pgrx to 0.12.4 and adds PG 17 support

[davidgomes]

What kind of change does this PR introduce?

This PR bumps the pgrx version to 0.12.4 so that PG17 can be supported.

What is the new behavior?

$ cargo pgrx run pg16
    Starting Postgres v16 on port 28816
     Creating database pg_jsonschema
psql (16.4)
Type "help" for help.

david@pg_jsonschema=# create extension pg_jsonschema;
CREATE EXTENSION
Time: 252.695 ms
david@pg_jsonschema=# select json_matches_schema('{"type": "object"}', '{}');
┌─────────────────────┐
│ json_matches_schema │
├─────────────────────┤
│ t                   │
└─────────────────────┘
(1 row)

Time: 10.122 ms
david@pg_jsonschema=# ^D\q

$ cargo pgrx run pg17
    Starting Postgres v17 on port 28817
     Creating database pg_jsonschema
psql (17rc1)
Type "help" for help.

david@pg_jsonschema=# create extension pg_jsonschema;
CREATE EXTENSION
Time: 246.665 ms
david@pg_jsonschema=# select json_matches_schema('{"type": "object"}', '{}');
┌─────────────────────┐
│ json_matches_schema │
├─────────────────────┤
│ t                   │
└─────────────────────┘
(1 row)

Time: 9.595 ms
david@pg_jsonschema=# ^D\q

[imor]

@davidgomes could you please bump pgrx at these locations as well:

• pg_jsonschema/.github/workflows/release.yml

  Line 43 in 4ba6b23

  - 0.11.3

• pg_jsonschema/dockerfiles/db/Dockerfile

  Line 30 in 4ba6b23

  RUN cargo install cargo-pgrx --version 0.11.3 --locked

And also rebase on master once this PR is merged.

[davidgomes]

@davidgomes could you please bump pgrx at these locations as well:

• pg_jsonschema/.github/workflows/release.yml

  Line 43 in 4ba6b23

  - 0.11.3

• pg_jsonschema/dockerfiles/db/Dockerfile

  Line 30 in 4ba6b23

  RUN cargo install cargo-pgrx --version 0.11.3 --locked

And also rebase on master once this PR is merged.

Oh, I'm super sorry I totally missed the CI part of this 😞