ci: mipsel-softfloat — use mipsel-musl image + RUSTFLAGS=+soft-float #40

Job	Run time
android	12m 26s
build (x86_64-unknown-linux-musl, ubuntu-latest, mhrv-rs-linux-musl-amd64)	2m 11s
build (mipsel-unknown-linux-musl, ubuntu-latest, mhrv-rs-openwrt-mipsel-softfloat, true)	1m 2s
build (aarch64-unknown-linux-gnu, ubuntu-22.04, mhrv-rs-linux-arm64)	2m 13s
build (aarch64-apple-darwin, macos-latest, mhrv-rs-macos-arm64)	4m 13s
build (aarch64-unknown-linux-musl, ubuntu-latest, mhrv-rs-linux-musl-arm64)	2m 18s
build (x86_64-unknown-linux-gnu, ubuntu-22.04, mhrv-rs-linux-amd64)	5m 44s
build (arm-unknown-linux-gnueabihf, ubuntu-22.04, mhrv-rs-raspbian-armhf)	2m 8s
build (x86_64-pc-windows-gnu, windows-latest, mhrv-rs-windows-amd64)	9m 37s
build (x86_64-apple-darwin, macos-latest, mhrv-rs-macos-amd64)	4m 18s
release	23s
telegram	12s
	46m 45s

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