Avoid deleting the collective-folder with dcs

First of all: Awesome software! I highly appreciate it.

I have a very small issue that I don't manage to resolve:

I mounted a cifs directory into my dsc container, enabling it to fetch new scanned documents from my NAS. This works flawlessly. Unfortunately, the "--delete"-flag not only deletes the imported pdf-files but the collective directories (inside /opt/docs/[collective]) too. This is quite problematic as my scanner is sending the scans there. This will fail if the directory is not existent.

How can this behaviour be avoided?

```
image: docspell/dsc:latest
container_name: docspell-consumedir
command:
- dsc
- "-d"
- "http://docspell-restserver:7880"
- "upload"
- "--matches"
- "**/*.pdf"
- "--traverse"
- "--poll"
- "120"
- "--delete"
- "-i"
- "--not-matches"
- "**/.*"
- "--header"
- "Docspell-Integration:xxx"
- "/opt/docs"
```