When install decap-cms-widget-markdown, it throw unmet peer error

```text
└─┬ decap-cms-widget-markdown 3.1.3
├─┬ remark-slate-transformer 0.7.5
│ └── ✕ unmet peer unified@>=10.1.0: found 9.2.2 in decap-cms-widget-markdown
├─┬ slate-base64-serializer 0.2.115
│ └── ✕ unmet peer slate@">=0.32.0 <0.50.0": found 0.91.4 in decap-cms-widget-markdown
└─┬ slate-plain-serializer 0.7.13
└── ✕ unmet peer slate@">=0.46.0 <0.50.0": found 0.91.4 in decap-cms-widget-markdown
```

This is because on slate version above 0.50 no longer requires separate serializer.
https://github.com/decaporg/decap-cms/blob/cdd0899c3d1b2aada5ea6e8a983499ec099814f5/packages/decap-cms-widget-markdown/package.json#L37

ref: https://github.com/ianstormtaylor/slate/blob/d0d4c6364939116d494455445891858ac5457aeb/docs/concepts/xx-migrating.md?plain=1#L35