Use cargo home instead

Author: jdetter

.github/workflows/csharp-test.yml

@@ -85,7 +85,7 @@ jobs:
           cargo install --force --path crates/cli --locked --message-format=short
           cargo install --force --path crates/standalone --locked --message-format=short
           # Add a handy alias using the old binary name, so that we don't have to rewrite all scripts (incl. in submodules).
-          ln -sf $HOME/.cargo/bin/spacetimedb-cli $HOME/.cargo/bin/spacetime
+          ln -sf $CARGO_HOME/bin/spacetimedb-cli $CARGO_HOME/bin/spacetime
         env:
           # Share the target directory with our local project to avoid rebuilding same SpacetimeDB crates twice.
           CARGO_TARGET_DIR: demo/Blackholio/server-rust/target