Fix building Docker image for cross-compilation [dev branch]

[starypatyk]

The changes to the Docker build made for the old-api branch in #1289 are also required in the dev branch.

Changes cherry-picked from the original commit.

• Debian stretch packages are now available only from archive.debian.org
• Use rust 1.71 - MIPS target demoted to tier 3 at 1.72

With these changes I have been able to build the dev branch for all architectures except MIPS.

Does it still make sense to maintain the MIPS architecture? Are there any known uses of librespot on MIPS devices?

[roderickvd]

Thanks. Support for MIPS is hardly a goal…