Refactor LoggerFileTarget to use instance locking for improved thread safety

Author: fembina

Sources/Falko.ZeroLogger.Targets.File/Targets/LoggerFileTarget.cs

@@ -21,9 +21,9 @@ public sealed class LoggerFileTarget : LoggerTarget
     private static readonly string ApplicationDirectory = AppDomain.CurrentDomain.BaseDirectory;
 
 #if NET9_0_OR_GREATER
-    private static readonly Lock Locker = new();
+    private readonly Lock _locker = new();
 #else
-    private static readonly object Locker = new();
+    private readonly object _locker = new();
 #endif
 
     private readonly string _directoryPath;