[bug-fix] Fix sequence length buffer truncate

[ervteng]

Proposed change(s)

Fixed an issue where if 80% of the buffer isn't a multiple of sequence length, we'll get weird sequences in the buffer. Only affects SAC with LSTM.

Types of change(s)

• [x] Bug fix
• [ ] New feature
• [ ] Code refactor
• [ ] Breaking change
• [ ] Documentation update
• [ ] Other (please describe)

Checklist

• [x] Added tests that prove my fix is effective or that my feature works
• [x] Updated the changelog (if applicable)
• [ ] Updated the documentation (if applicable)
• [ ] Updated the migration guide (if applicable)

Other comments

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