use no-self-update

Author: Eh2406

ci/azure-install-rust.yml

@@ -18,7 +18,7 @@ steps:
       set -e
       rustup set profile minimal
       rustup component remove --toolchain=$TOOLCHAIN rust-docs || echo "already removed"
-      rustup update $TOOLCHAIN
+      rustup update --no-self-update $TOOLCHAIN
       rustup default $TOOLCHAIN
     displayName: Install rust