add rustc-dev

Author: Eh2406

ci/azure-install-rust.yml

@@ -15,6 +15,7 @@ steps:
       rustup set profile minimal
       rustup component remove --toolchain=$TOOLCHAIN rust-docs || echo "already removed"
       rustup update --no-self-update $TOOLCHAIN
+      rustup component add --toolchain=$TOOLCHAIN rustc-dev
       rustup default $TOOLCHAIN
     displayName: Install rust