json in unmaintained

RUSTSEC advisory for this dependency has been was reported in 2022

https://rustsec.org/advisories/RUSTSEC-2022-0081

A warning appears when using cargo audit with a dependency tree of

```
json 0.12.4
└── xee-interpreter 0.2.0
    └── xee-xpath-compiler 0.1.5
        └── xee-xpath 0.1.5
```