fix date for Keyspace CN event (#413)

### Description

The fontmatter on the page didn't match the event date and caused the
`/events/ page to have an incorrect date.

### Issues Resolved

n/a

### Check List
- [x] Commits are signed per the DCO using `--signoff`

By submitting this pull request, I confirm that my contribution is made
under the terms of the BSD-3-Clause License.

Signed-off-by: Kyle J. Davis <kyledvs@amazon.com>

Author: stockholmux

content/events/keyspace-beijing-2025/index.md

@@ -1,6 +1,6 @@
 +++
 title = "Keyspace Beijing 北京"
-date= 2025-08-28 01:01:01
+date= 2025-12-13 01:01:01
 
 [extra]
 body_class = "keyspace-2025"