Avoid matching multi-line imports (#43093)

Multi-line imports are broken:
```
use Illuminate\Foundation\Testing\{
    DatabaseTransactions,
    WithFaker,
};
```
Results in output:
```
    DatabaseTransactions,
    WithFaker,
use Illuminate\Foundation\Testing\{
};
```

src/Illuminate/Console/GeneratorCommand.php

@@ -351,7 +351,7 @@ protected function replaceClass($stub, $name)
      */
     protected function sortImports($stub)
     {
-        if (preg_match('/(?P<imports>(?:use [^;]+;$\n?)+)/m', $stub, $match)) {
+        if (preg_match('/(?P<imports>(?:use [^;{]+;$\n?)+)/m', $stub, $match)) {
             $imports = explode("\n", trim($match['imports']));
 
             sort($imports);