Update qore-pqsql-module to version 2.4.

Patches have been applied upstream.

Release notes:

* placeholders and quotes in SQL comments are ignored
* fixed major bugs in SQLStatement::fetchRows() and
  SQLStatement::fetchColumns() where only the first call would succeed
* added the pgsql_bind_array() function to support bulk DML
* fixed a bug retrieving numeric values; values too large for a 64-bit integer
  were being retrieved as a 64-bit integer
* ported db-test.q to new-style and QUnit
* changed the minimum required Qore version to 0.8.12 to support
  the test script wth QUnit
* fixed a bug where interval values retrieved from the DB were justified
  to hours and minutes
* fixed a bug where CHAR values were returned with an invalid internal string
  size
* fixed a bug where arbitrary-precision numeric values bound to numeric
  columns were bound with an incorrect scale value causing the digits
  behind the decimal place to be lost (issue 386)
* fixed a bug where SQLStatement::describe() was failing even though result
  set information was available
* fixed a bug where duplicate column names in result sets caused
  memory leaks (and they were not renamed; issue 831)

(nros)