REL4_3_0

This minor version of set_user includes the following important security fixes and changes:

• Fix security issues that let a session escalated by set_user() return to the original role without the reset token or crash the backend.
• Fix allowlist matching of group entries and match role names case-sensitively.
• Compare reset tokens in constant time.
• Remove support for PostgreSQL 13.
• Document the limits of the reset token.