feat: process messages according to PSR-3

Add PSR processor, to handle inline variables in log statements, like
"Registering user {id} with name {full_name}".

https://www.php-fig.org/psr/psr-3/#12-message



Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

src/SimpleLoggerFactory.php

@@ -7,6 +7,7 @@ use Monolog\Handler\HandlerInterface;
 use Monolog\Handler\NullHandler;
 use Monolog\Logger;
 use Monolog\Handler\ErrorLogHandler;
+use Monolog\Processor\PsrLogMessageProcessor;
 use WPDesk\Logger\WC\WooCommerceHandler;
 
 final class SimpleLoggerFactory implements LoggerFactory {
@@ -30,7 +31,11 @@ final class SimpleLoggerFactory implements LoggerFactory {
 			return $this->logger;
 		}
 
-		$this->logger = new Logger( $this->channel );
+		$this->logger = new Logger(
+			$this->channel,
+			[],
+			[ new PsrLogMessageProcessor( null, true ) ]
+		);
 
 		if ( $this->options->use_wc_log ) {
 			if ( \function_exists( 'wc_get_logger' ) && \did_action( 'woocommerce_init' ) ) {