Update `bindgen` to `0.70` #350

Job	Run time
rust_clippy_check_windows	1m 51s
build_static_and_test_ubuntu_with_system_ffmpeg	1m 3s
build_static_and_test_ubuntu	5m 47s
rust_clippy_check_ubuntu	6m 42s
rustfmt_check (macos-latest)	6s
build_dynamic_and_test_ubuntu	1m 47s
rustfmt_check (windows-latest)	24s
build_dynamic_and_test_macos	2m 2s
build_dynamic_and_test_windows_pre	2m 23s
rustfmt_check (ubuntu-latest)	5s
docs_rs_check	1m 14s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static, -Ctarget-feature=+cr...	1m 25s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md)	1m 21s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows, true)	1m 57s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static, -Ctarget-feature=+crt-...	1m 28s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static-md)	2m 3s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows, true)	1m 45s
build_dynamic_and_test_windows	1m 48s
	35m 11s

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