Update readme for `0.15.0+ffmpeg.7.0` (#177) #457

Job	Run time
rust_clippy_check_ubuntu	6m 15s
build_dynamic_and_test_windows_pre	6m 5s
docs_rs_check	51s
build_static_and_test_ubuntu (release/6.0, nightly, no valgrind)	5m 22s
rust_clippy_check_windows	5m 18s
build_static_and_test_ubuntu (release/6.0, 1.70.0, no valgrind)	5m 31s
rustfmt_check (macos-latest)	9s
build_static_and_test_ubuntu (release/6.1, nightly, no valgrind)	6m 9s
rustfmt_check (windows-latest)	19s
build_static_and_test_ubuntu (release/6.1, 1.70.0, no valgrind)	5m 37s
rustfmt_check (ubuntu-latest)	14s
build_static_and_test_ubuntu (release/7.0, nightly, valgrind)	43m 50s
build_static_and_test_ubuntu (release/7.0, nightly, no valgrind)	6m 32s
build_static_and_test_ubuntu (release/7.0, 1.70.0, no valgrind)	5m 55s
build_dynamic_and_test_windows (nightly)	1m 39s
build_dynamic_and_test_windows (1.70.0)	1m 38s
	1h 41m 24s

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