Add changelog for `0.15.0` #453

Job	Run time
rust_clippy_check_windows	3m 22s
rust_clippy_check_ubuntu	5m 59s
build_dynamic_and_test_windows_pre	6m 6s
build_static_and_test_ubuntu (release/6.0, nightly, no valgrind)	5m 13s
docs_rs_check	55s
rustfmt_check (macos-latest)	9s
build_static_and_test_ubuntu (release/6.0, 1.70.0, no valgrind)	5m 15s
rustfmt_check (windows-latest)	32s
build_static_and_test_ubuntu (release/6.1, nightly, no valgrind)	5m 28s
rustfmt_check (ubuntu-latest)	5s
build_static_and_test_ubuntu (release/6.1, 1.70.0, no valgrind)	5m 34s
build_static_and_test_ubuntu (release/7.0, nightly, valgrind)	43m 45s
build_static_and_test_ubuntu (release/7.0, nightly, no valgrind)	6m 31s
build_static_and_test_ubuntu (release/7.0, 1.70.0, no valgrind)	6m 10s
build_dynamic_and_test_windows (nightly)	1m 41s
build_dynamic_and_test_windows (1.70.0)	1m 58s
	1h 38m 43s

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