PG Exporter v0.3.1

VonngAuthor of PG Exporter and Pigsty, working on PostgreSQL infrastructure and monitoring.

Changes

Fixed default-configuration errors, especially on PostgreSQL versions below 13:

• Restricted primary_conninfo collection to the supported collector branch.
• Added funcid to pg_func labels to distinguish functions with the same name.
• Corrected the program name in version output to pg_exporter.