pip field in environment.yml fails linting

[edmundmiller]

│ spotiflow    │ modules/nf-core/spotiflow/en… │ The environment.yml of the    │
│              │                               │ module spotiflow is not       │
│              │                               │ valid: {'pip': ['spotiflow']} │
│              │                               │ is not of type 'string'.      │
│              │                               │ Check the entry for           │
│              │                               │ dependencies.                 │

"There's a pip: in my dependencies"

[famosab]

Should be solved by: #6588