Bump bindgen to 0.72 for LLVM 22 compatibility

[iovxw]

Bumps bindgen from 0.71 to 0.72 to fix compilation on systems with LLVM/Clang 22.

Problem

LLVM 22 introduced a change in AST representation (llvm/llvm-project#147835) that
causes bindgen 0.71 to incorrectly generate opaque types for several FFmpeg structs
(e.g., AVFormatContext, AVBitStreamFilter). This makes any crate depending on
rusty_ffmpeg fail to compile on LLVM 22 systems.

The issue was reported and fixed in bindgen 0.72.1:

• Missing fields in nested class with LLVM 22 rust-lang/rust-bindgen#3264
• rust-lang/rust-bindgen@v0.72.0...v0.72.1

Testing

• Verified on LLVM 22.1.2 with FFmpeg 6.1.1 headers
• The bindgen 0.72 release is backward compatible with older LLVM versions,
  so this should not break CI on Ubuntu with older clang

[Copilot]

Pull request overview

Updates the crate’s build-time binding generation dependency to address bindgen incompatibilities with LLVM/Clang 22, preventing incorrect opaque type generation for some FFmpeg structs on those systems.

Changes:

• Bump bindgen build-dependency from 0.71 to 0.72 in Cargo.toml.

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[ldm0]

Thanks, will release tonight.