Update check_links_config.json

Author: lzchen

.github/workflows/check_links_config.json

@@ -10,7 +10,7 @@
             "pattern": "http(s)?://example.com"
         },
         {
-            "pattern": "^\d{4}-\d{2}-\d{2}$"
+            "pattern": "^\\d{4}-\\d{2}-\\d{2}$"
         }
     ],
     "aliveStatusCodes": [429, 200]