Merge #113

113: bump version to v0.9.0 due to breaking changes r=Disasm a=almindor

As per discussion on https://github.com/rust-embedded/riscv/pull/112

 we want to release `v0.9.0` and yank `v0.8.1` since the removals were a breaking change.

Co-authored-by: Ales Katona <ales@katona.me>