Use php-fpm instead of mod_php, enable http2 (#11 and #28)

Closes #11 (closed) and #28 (closed)

lib/os/class.ISPConfigDebianOS.inc.php

@@ -161,15 +161,9 @@ class ISPConfigDebianOS extends ISPConfigBaseOS {
 		$modules = array(
 			'mpm_prefork'
 		);
-
-		if(ISPConfig::wantsPHP() === 'system') {
-			array_unshift($modules, 'php' . $this->getSystemPHPVersion());
-		} else {
+		if(ISPConfig::wantsPHP() !== 'system') {
 			array_unshift($modules, 'php8.0');
-			);
 		}
-	}
-
 		return $modules;
 	}
 
@@ -814,7 +808,7 @@ mailman-unsubscribe:  "|/var/lib/mailman/mail/mailman unsubscribe mailman"';
 		if(ISPConfig::wantsPHP() === 'system') {
 			$php_versions = array($this->getSystemPHPVersion());
 		} else {
-			// If a new version is added, the getApacheModulesToDisable function should be updated to disable the latest version
+			// If a new version is added, the getApacheModulesToDisable function should be updated to disable the latest version (this part could be improved)
 			$php_versions = array(
 				'5.6',
 				'7.0',