Update MediaUploader ref to master (adds a merge commit only)

[dannyroberts]

Summary

I had made dimagi/MediaUploader#29 along with #29489.

Product Description

None

Safety Assurance

• Risk label is set correctly
• All migrations are backwards compatible and won't block deploy
• The set of people pinged as reviewers is appropriate for the level of risk of the change
• If QA is part of the safety story, the "Awaiting QA" label is used
• I have confidence that this PR will not introduce a regression for the reasons below

Automated test coverage

There is no code change

QA Plan

There is no code change

Safety story

There is no code change. The submodule ref is being updated to include one more commit which is a merge commit (merging in the PR) that has no code changes in itself.

Rollback instructions

• This PR can be reverted after deploy with no further considerations