Switched YAMNet to stick with Keras 2.

[plakal]

Description

Switched YAMNet to stick with Keras 2. TF 2.16 switched the default to Keras 3 which is backwards incompatible.

closes #11212

Type of change

For a new feature or function, please create an issue first to discuss it with us before submitting a pull request.

Note: Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Documentation update
• [ ] TensorFlow 2 migration
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] A new research paper code implementation
• [ ] Other (Specify)

Tests

Installed latest versions of all dependences (including new tf_keras) and ran yamnet_test.py

Test Configuration:

Checklist

• [x] I have signed the Contributor License Agreement.
• [x] I have read guidelines for pull request.
• [x] My code follows the coding guidelines.
• [x] I have performed a self code review of my own code.
• [ ] I have commented my code, particularly in hard-to-understand areas.
• [x] I have made corresponding changes to the documentation.
• [x] My changes generate no new warnings.
• [ ] I have added tests that prove my fix is effective or that my feature works.