Update pgvector v0.7.2

What does this merge request do and why?

This MR bumps the pgvector version to v0.7.2 in order to leverage HNSW indexes which were introduced in v0.5.0.

How to set up and validate locally

1. Ensure pgvector is is enabled by adding the below configuration in gdk.yml:

pgvector:
  enabled: true
  version: v0.7.2

1. Run gdk reconfigure to check if regenerating all configuration is successful.

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.