merge apt-get commands

ci/docker/mips64-unknown-linux-gnuabi64/Dockerfile

@@ -7,7 +7,7 @@ RUN apt-get update && \
     libc6-dev \
     libc6-dev-mips64-cross \
     qemu-user-static \
-    apt-get install -y --no-install-recommends qemu-system-mips
+    qemu-system-mips
 ENV CARGO_TARGET_MIPS64_UNKNOWN_LINUX_GNUABI64_LINKER=mips64-linux-gnuabi64-gcc \
     CC_mips64_unknown_linux_gnuabi64=mips64-linux-gnuabi64-gcc \
     QEMU_LD_PREFIX=/usr/mips64-linux-gnuabi64 \