changes: 8.21.0 release video

Author: bagder

_changes.html

@@ -56,6 +56,7 @@
 
 <a name="8_21_0"></a>
 SUBTITLE(Fixed in 8.21.0 - June 24 2026)
+RELEASEVIDEO(8.21.0, "https://youtu.be/yVXnTNINI2I")
 <p> Changes:
 <ul class="changes">
  CHG <a href="https://curl.se/bug/?i=21407">curl: named globs in output filename for upload glob references</a>