After updating to macOS Big Sur I can't connect to my PostgreSQL database with MAMP

Code

Here's the code that is throwing the error.

try {
  $myPDO = new PDO('pgsql:host=127.0.0.1:5432;dbname=test', 'test', '');
} catch (\Throwable $th) {
  echo var_dump($th);
}

Error

Here's the response I'm getting back from the try/catch.

object(PDOException)#2 (8) {
  ["message":protected]=>
  string(21) "could not find driver"
  ["string":"Exception":private]=>
  string(0) ""
  ["code":protected]=>
  int(0)
  ["file":protected]=>
  string(58) "/Users/test/index.php"
  ["line":protected]=>
  int(8)
  ["trace":"Exception":private]=>
  array(1) {
    [0]=>
    array(6) {
      ["file"]=>
      string(58) "/Users/test/index.php"
      ["line"]=>
      int(8)
      ["function"]=>
      string(11) "__construct"
      ["class"]=>
      string(3) "PDO"
      ["type"]=>
      string(2) "->"
      ["args"]=>
      array(3) {
        [0]=>
        string(46) "pgsql:host=127.0.0.1:5432;dbname=test"
        [1]=>
        string(13) "test"
        [2]=>
        string(0) ""
      }
    }
  }
  ["previous":"Exception":private]=>
  NULL
  ["errorInfo"]=>
  NULL
}

Versions

A list of the software versions I'm using.

OS: macOS Big Sur

MAMP: 6.2

PHP: 7.3.21

Update - More Context

In the php.ini file the following lines are uncommented. This is the correct php.ini file according to PHP Info.

extension_dir = "/Applications/MAMP/bin/php/php7.4.9/lib/php/extensions/no-debug-non-zts-20190902/"
...
extension=pgsql.so
extension=pdo_pgsql.so