Update contest data

contests_all.json

@@ -1,5 +1,5 @@
 {
-  "generated_at": 1788828243,
+  "generated_at": 1788844868,
   "contests": [
     {
       "platform": "AtCoder",
@@ -1201,6 +1201,14 @@
       "status": "upcoming",
       "url": "https://atcoder.jp/contests/agc078"
     },
+    {
+      "platform": "AtCoder",
+      "title": "AtCoder Beginner Contest 478",
+      "start_time": 1791028800,
+      "end_time": 1791034800,
+      "status": "upcoming",
+      "url": "https://atcoder.jp/contests/abc478"
+    },
     {
       "platform": "AtCoder",
       "title": "AAL Contest 001: Let's use segtree!",