Fix date for "Concert nadal 2020 joves i adults"

Change-Id: I7ccf9c27ee6d12a2209220c4c568dde487e87334
diff --git a/concerts/nadal2020joves.json b/concerts/nadal2020joves.json
index 4628e00..93c6542 100644
--- a/concerts/nadal2020joves.json
+++ b/concerts/nadal2020joves.json
@@ -1,7 +1,7 @@
 {
   "title": "Concert de Nadal 2020",
   "subtitle": "Joves i adults",
-  "begins": 1608227730,
+  "begins": 1608312600,
   "songs": [
     {
       "title": "Santa Nit",