feat(compute): Allow installing both 0.8.0 and 0.7.4 pgvector

[ololobus]

Problem

Both these versions are binary compatible, but the way pgvector structures the SQL files forbids installing 0.7.4 if you have a 0.8.0 distribution. Yet, some users may need a previous version for backward compatibility, e.g., restoring the dump.

See this thread for discussion
https://neondb.slack.com/archives/C04DGM6SMTM/p1735911490242919?thread_ts=1731343604.259169&cid=C04DGM6SMTM

Summary of changes

Put vector--0.7.4.sql file into compute image to allow installing this version as well.

Tested on staging and it seems to be working as expected:

select * from pg_available_extensions where name = 'vector';
  name  | default_version | installed_version |                       comment                        
--------+-----------------+-------------------+------------------------------------------------------
 vector | 0.8.0           | (null)            | vector data type and ivfflat and hnsw access methods

create extension vector version '0.7.4';

select * from pg_available_extensions where name = 'vector';
  name  | default_version | installed_version |                       comment                        
--------+-----------------+-------------------+------------------------------------------------------
 vector | 0.8.0           | 0.7.4             | vector data type and ivfflat and hnsw access methods

alter extension vector update;

select * from pg_available_extensions where name = 'vector';
  name  | default_version | installed_version |                       comment                        
--------+-----------------+-------------------+------------------------------------------------------
 vector | 0.8.0           | 0.8.0             | vector data type and ivfflat and hnsw access methods

drop extension vector;
create extension vector;

select * from pg_available_extensions where name = 'vector';
  name  | default_version | installed_version |                       comment                        
--------+-----------------+-------------------+------------------------------------------------------
 vector | 0.8.0           | 0.8.0             | vector data type and ivfflat and hnsw access methods

If we find out it's a good approach, we can adopt the same for other extensions with a stable ABI -- support both current and current - 1 releases.

[github-actions]

7282 tests run: 6917 passed, 0 failed, 365 skipped (full report)

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Flaky tests (1)

Postgres 16

• test_create_churn_during_restart: release-arm64

Code coverage* (full report)

• functions: 32.7% (8042 of 24618 functions)
• lines: 47.8% (66813 of 139908 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
4991520 at 2025-01-10T16:28:15.102Z :recycle:}