ci: remove workaround for riscv64

Author: kxxt

ci/test.sh

@@ -48,10 +48,6 @@ main() {
         # don't use xargo: should have native support just from rustc
         rustup toolchain add nightly
         CROSS+=("+nightly")
-    elif [[ "${TARGET}" == "riscv64gc-unknown-linux-gnu" ]]; then
-        # FIXME: riscv64gc-unknown-linux-gnu is broken on rustc 1.75, see https://github.com/cross-rs/cross/issues/1423
-        rustup toolchain add 1.70
-        CROSS+=("+1.70")
     fi
 
     if (( ${STD:-0} )); then