update www/seahub to 6.0.7

Changes: https://seacloud.cc/group/3/wiki/server-changelog

• [fix] Fix generating of password protected link in file view page
• [fix] Fix .jpg/.JPG image display in IE10
• Export quota usage in export Excel in user list admin page
• [fix] Fix admin can't delete broken libraries
• Add "back to previous page" link in trash page, history page
• [fix] Improve logo show in About page
• [fix] Fix file encoding for text file editing online
• [fix] Don't show operation buttons for broken libraries in normal users page

PR: 216349
Submitted by: ultima1252@gmail.com (maintainer)
Reviewed by: matthew
Approved by: matthew (mentor)
Differential Revision: https://reviews.freebsd.org/D9284