cancel SIG Std/Cert meeting on 2025-08-14 (#386)

Signed-off-by: Marvin Frommhold <[email protected]>

Author: depressiveRobot

teams/sig_standard_cert/team_meetings.yml

@@ -87,3 +87,4 @@ events:
         - 2025-05-29 14:05:00  # Ascension day
         - 2025-06-05 14:05:00  # because of FOCIS hackathon
         - 2025-06-19 14:05:00  # public holiday in southern Germany, and others are gone as well
+        - 2025-08-14 14:05:00  # holiday season; most people are on vacation