Update av requirement from ~=15.0 to ~=15.1

[dependabot]

Updates the requirements on av to permit the latest version.

Release notes

Sourced from av's releases.

v15.1.0

Full Changelog: PyAV-Org/PyAV@v15.0.0...v15.1.0

Changelog

Sourced from av's changelog.

v15.1.0

Features:

• Support FFmpeg 8
• Make the Frame.key_frame flag writable.

v15.0.0

Major:

• Make SubtitleStream.decode() return the list of subtitles directly, making the API nicer.
• Drop support for MacOS 12 or under.
• Binary wheels: Remove libxml2 because of security concerns.
• Binary wheels: Remove xz because lzma encoding is very niche in media decoding and lesser security concerns.

Features:

• Add GBRP, GBRAP, RGBA formats by :gh-user:z-khan.
• Add VideoFrame.save(), a convenient way to save frames to PNGs or JPEGs, by :gh-user:WyattBlue.

Fixes:

• Binary wheels: Re-enable libx265, use version 4.1 by :gh-user:WyattBlue.
• Fix memory error for AudioFifo properties by :gh-user:zzjjbb.
• Copy template flags if creating a new Codec object by :gh-user:WyattBlue
• AudioFrame.from_ndarray(): Support python classes for parameters too, by :gh-user:WyattBlue.

v14.4.0

Features:

• Expose the duration field for frames by :gh-user:Queuecumber in (:pr:1880).
• Add support for BGR48 and BGRA64 pixel formats by :gh-user:z-khan in (:pr:1873).

Fixes:

• Fix security vulnerabilities in binary wheels by :gh-user:jlaine in (:pr:1896).

v14.3.0

Features:

• Support yuv420p10le in numpy conversion by :gh-user:tsnl in (:pr:1833).
• Add typing overloads for CodecContext.create by :gh-user:jlaine in (:pr:1853).
• Provide binary wheels for musl-based distros such as Alpine by :gh-user:jlaine in (:pr:1856).

... (truncated)

Commits

• e3f2efd Don't build i686 binaries
• 7247411 Release 15.1.0
• 0b85c60 Build with ffmpeg 8
• 22d6a7a Remove unused swr functions
• eaa675d Remove FilterFlags
• 3de331d Combine pad and link
• 2f6c495 Replace FFmpeg version macro with direct API call
• 3cb9b63 Fix opaque container on PyPy
• e2ec340 Index opaque by id and make key_frame writable
• 8e973ab Add set_image for updating the image content of an existing frame
• Additional commits viewable in compare view

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[dependabot]

Superseded by #96.