bundle: false rewrites "with { type: 'json' }" to deprecated "assert { type: 'json' }"

```ts
import {defineConfig} from 'tsup';

const config = defineConfig({
entry: [
'src/**/*.{js,cjs,mjs,ts,mts,json}'
],

platform: 'node',
// target: 'esnext',
outDir: './dist',
clean: true,
dts: true,
format: 'esm',
treeshake: true,
splitting: true,
bundle: false
});

export default config;
```

```ts
import data from '#foo/file.json' with {type: 'json'};
```

is being replaced with the deprecated syntax:

```ts
import data from '#foo/file.json' assert {type: 'json'};
^ SyntaxError: Unexpected identifier 'assert'
```

Start with the provided tsup configuration using `bundle: false` and the JSON import containing `with { type: 'json' }`; reproduce the output transformation and trace the path handling this syntax. Done means the emitted import retains the `with` form and no longer produces the deprecated `assert` syntax or the shown SyntaxError.

Written by the indexing model from the issue text.