Update SVT-AV1 to v1.8.0

[n00mkrad]

Updates the SVT-AV1 repo commit to 5fbddb53b3dc1a32f35ade563e2f6d32dc500417.

Old version is v1.7.0-17-ga49c786a.

Chanelog below

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Encoder

• Improve the tradeoffs for the random access mode across presets:
• Speedup CRF presets M6 to M0 by 17-53% while maintaining similar quality levels
• Re-adjust CRF presets M7 to M13 for better quality with BD-rate gains ranging from 1-4%
• Improve the quality and speed of the 1-pass VBR mode
• More details on the per preset improvements can be found in MR !2143
• Add API allowing to update bitrate / CRF and Key_frame placement during the encoding session for CBR lowdelay mode and CRF Random Access mode
• ARM Neon SIMD optimizations for most critical kernels allowing for a 4.5-8x fps speedup vs the c implementation

Cleanup and bug fixes and documentation

• Various cleanups and functional bug fixes
• Update the documentation for preset options and individual features

[BtbN]

I somehow missed this. Should have been part of the last dependency updated already.