fix language (#1336)

Author: maelle

content/events/2026-07-06-charlas-rse-espanol.md

@@ -8,6 +8,7 @@ location: 'Bentham House UCL, Tutorial Room 302, Endsleigh Gardens, London WC1H
 slug: 'charlas-rse-espanol-2026-07-06'
 country: "🇬🇧" # emoji
 ropensci: no
+lang: Español
 outputs:
   - HTML
   - Calendar