Incorrect TypeScript to OpenApi enums mapping when stripping annotations

First of all, thanks for cool package! It seems to work great compared to other similar packages. However I found one issue.

When using `--strip-annotations` flag it changes the way how enums are converted.

Given this typescript code:

```ts
export type Side = "left" | "right";
```

By default it converts to this YAML, which seems to be correct:

```yaml
Side:
enum:
- left
- right
title: Side
type: string
```

But when `--strip-annotations` flag is used, it get's converted to wrong `anyOf` format:

```yaml
Side:
anyOf:
- enum:
- left
type: string
- enum:
- right
type: string
```

When using `--strip-annotations` it's expected to not change the way how enums are converted.