Bump `bindgen` to `0.69` #303

Job	Run time
build_static_and_test_ubuntu_with_system_ffmpeg	1m 1s
rust_clippy_check_windows	26m 53s
build_dynamic_and_test_ubuntu	2m 3s
build_dynamic_and_test_windows_pre	3m 17s
build_dynamic_and_test_macos	3m 17s
build_static_and_test_ubuntu	5m 21s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static, -Ctarget-feature=+cr...	27m 3s
docs_rs_check	1m 18s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md)	26m 5s
rust_clippy_check_ubuntu	5m 16s
rustfmt_check (macos-latest)	19s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows, true)	27m 6s
rustfmt_check (windows-latest)	36s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static, -Ctarget-feature=+crt-...	26m 50s
rustfmt_check (ubuntu-latest)	12s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static-md)	25m 37s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows, true)	26m 14s
build_dynamic_and_test_windows	2m 2s
	3h 30m 30s

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