Added workarounds for Proofpoint in-transit certificate email attachment modification

In July 2024, customers using Conferences i/o to send attendance certificates began reporting that sometimes recipients would receive certificate attachment PDFs that were blank or otherwise corrupted.

It was determined that an email security service called Proofpoint was modifying underlying structural data in the attachments.

While we still don't know why Proofpoint was doing this, a change was introduced to work-around this behavior.

Miscellaneous improvements and bug fixes

• Slide music uploads now supports MP3 and WAV, and up to 10 MB files.
• Fixed bug where merging checkins could cause inaccurate duration calculation in some scenarios.
• Fixed bug where sponsor name was being saved to attendance tracking content settings page.
• Fixed bug that was allowing duplicate codewords to be created when auto-generating codewords.
• Fixed bug that allowed unintentional whitespace to be added to fields of study in some scenarios.