Update pgvector requirement from >=0.3.6 to >=0.4.2 in /ai-service

[dependabot]

Updates the requirements on pgvector to permit the latest version.

Changelog

Sourced from pgvector's changelog.

0.4.2 (2025-12-04)

• Added support for Django 6
• Added support for str objects for bit type with SQLAlchemy

0.4.1 (2025-04-26)

• Fixed SparseVector constructor for SciPy sparse matrices

0.4.0 (2025-03-15)

• Added top-level pgvector package
• Added support for pg8000
• Added support for bytes to Bit constructor
• Changed globally option to default to False for Psycopg 2
• Changed arrays option to default to True for Psycopg 2
• Fixed equality for Vector, HalfVector, Bit, and SparseVector classes
• Fixed indices and values methods of SparseVector returning tuple instead of list in some cases
• Dropped support for Python < 3.9

0.3.6 (2024-10-26)

• Added arrays option for Psycopg 2

0.3.5 (2024-10-05)

• Added avg function with type casting to SQLAlchemy
• Added globally option for Psycopg 2

0.3.4 (2024-09-26)

• Added schema option for asyncpg

0.3.3 (2024-09-09)

• Improved support for cursor factories with Psycopg 2

0.3.2 (2024-07-17)

• Fixed error with asyncpg and pgvector < 0.7

0.3.1 (2024-07-10)

• Fixed error parsing zero sparse vectors
• Fixed error with Psycopg 2 and pgvector < 0.7
• Fixed error message when vector type not found with Psycopg 3

0.3.0 (2024-06-25)

• Added support for halfvec, bit, and sparsevec types to Django

... (truncated)

Commits

• 2968f25 Version bump to 0.4.2 [skip ci]
• 674f5ba Updated checkout action [skip ci]
• e2986da Added support for Django 6
• e211ba4 Test with Python 3.14 on CI
• 1a72b75 Updated pgvector on CI
• c820a53 Simplified examples [skip ci]
• caf1a2e Added docs for binary quantization with SQLAlchemy [skip ci]
• dc9a8f9 Added test for binary quantization with re-ranking
• 33dee60 Added support for str objects for bit type with SQLAlchemy - #137
• ee3e71c Updated format for license identifier
• Additional commits viewable in compare view

[dependabot]

Looks like pgvector is no longer a dependency, so this is no longer needed.