downgrade to kirby v3

vendor/psr/log/Psr/Log/LogLevel.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Psr\Log;
+
+/**
+ * Describes log levels.
+ */
+class LogLevel
+{
+    const EMERGENCY = 'emergency';
+    const ALERT     = 'alert';
+    const CRITICAL  = 'critical';
+    const ERROR     = 'error';
+    const WARNING   = 'warning';
+    const NOTICE    = 'notice';
+    const INFO      = 'info';
+    const DEBUG     = 'debug';
+}