feat: add '*.m4a' to client.d.ts and constants

[m1san]

Description

Add '*.m4a' to client.d.ts and constants, this allows m4a files (used in similar fashion as mp3) to be recognized as expected.

Additional context

Followed the steps to a similar PR #15189

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines, especially the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Update the corresponding documentation if needed.
• Ideally, include relevant tests that fail without this PR but pass with it.

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