svn commit: r78489 - dev/arrow/apache-arrow-21.0.0-rc6

[brycemecum]

Author: brycemecum
Date: Thu Jul 31 19:42:27 2025
New Revision: 78489

Log:
Remove old Apache Arrow RC: apache-arrow-21.0.0-rc6/

Deleted:
   dev/arrow/apache-arrow-21.0.0-rc6/