🐛 fix: Modify import statement for "SourceCode" component

The import statement for the "SourceCode" component in "src/slots/PreviewerActions/index.tsx" has been changed from "dumi/theme/builtins/SourceCode" to "dumi/theme-default/builtins/SourceCode". This fix ensures that the correct component is imported and used in the code.

src/slots/PreviewerActions/index.tsx

@@ -1,6 +1,6 @@
 import { ActionIcon, TabsNav } from '@lobehub/ui';
 import { type IPreviewerProps, openCodeSandbox, openStackBlitz, useIntl } from 'dumi';
-import SourceCode from 'dumi/theme/builtins/SourceCode';
+import SourceCode from 'dumi/theme-default/builtins/SourceCode';
 import { Code, Code2, Codesandbox, MonitorUp, Zap } from 'lucide-react';
 import { type FC, type ReactNode, useState } from 'react';