ci: update ffmpeg branch to release/7.1 and add libbz2-dev #373

Job	Run time
rustfmt_check (windows-latest)	47s
rustfmt_check (macos-latest)	18s
rustfmt_check (ubuntu-latest)	15s
build_static_and_test_ubuntu_with_system_ffmpeg	1m 19s
rust_clippy_check_ubuntu	6m 35s
build_dynamic_and_test_ubuntu	2m 40s
build_dynamic_and_test_windows_pre	3m 0s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static, -Ctarget-feature=+cr...	1m 52s
build_dynamic_and_test_macos	1m 56s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static-md)	1m 52s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md)	1m 52s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static, -Ctarget-feature=+crt-...	1m 53s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows, true)	1m 53s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows, true)	1m 53s
rust_clippy_check_windows	1m 30s
docs_rs_check	1m 13s
build_static_and_test_ubuntu	6m 54s
build_dynamic_and_test_windows	1m 46s
	39m 28s

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