Hi,
Apologies on the delayed response,
I had to methods of going about it. My considerations would be on the taking a closer look into the layout for inductor, and also possibly lowering output capacitor value slightly. You may use smaller capacitances like 2.2 or 1uF to deviate lower or as increments.
You may also refer to this as another resource:
Audible Power Supply Noise | Article | MPS (monolithicpower.com)
Kind Regards,
Nouman