Update copyright year to 2026

- Added license header into Go files

src/go/pt-galera-log-explainer/regex/states.go

@@ -1,3 +1,16 @@
+// This program is copyright 2026 Percona LLC and/or its affiliates.
+//
+// THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
+// WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// This program is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, version 2.
+//
+// You should have received a copy of the GNU General Public License, version 2
+// along with this program; if not, see <https://www.gnu.org/licenses/>.
+
 package regex
 
 import (