dev: source cargo env files to find rustup

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>

.devcontainer/setup.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
 curl https://sh.rustup.rs -sSf | sh -s -- -y
+
+# Update current shell environment variables after install to find rustup
+. "$HOME/.cargo/env"
 rustup install stable
 bash install.sh