Prepare 0.15.3 release #832

Job	Run time
rustfmt-check	4s
clippy-test	51s
ubuntu-test	42s
asmjs-wasm32-test (wasm32-unknown-emscripten)	54s
cargo-publish	0s
android-apk-build	1m 38s
android-check	39s
ios-build	7m 17s
linux-check-and-test-armv7	1m 45s
macos-test	4m 38s
wasm32-bindgen-test (wasm32-unknown-unknown)	18s
wasm32-wasi-test (wasm32-wasi)	24s
wasm-beep-build	27s
windows-test (x86_64)	2m 50s
windows-test (i686)	2m 19s
	24m 46s

Provide feedback