try this in `.vscode/settings.json`

```json
{
  "rust-analyzer.check.allTargets": false,
  "rust-analyzer.check.noDefaultFeatures": true,
  "rust-analyzer.cargo.noDefaultFeatures": true,
  "rust-analyzer.cargo.target": "thumbv7em-none-eabi",
  "rust-analyzer.cargo.features": [
    "nightly",
  ],
}