Escaped slashes in keys are not understood

```
quicktype -s schema http://purl.allotrope.org/json-schemas/adm/lc-ms/REC/2023/09/lc-ms.tabular.schema
Error: Key m~1z not in schema object at http://purl.allotrope.org/json-schemas/qudt/REC/2023/09/units.schema#m~1z.
```

excerpt

```json
"m/z": {
"$asm.property-class": "http://purl.allotrope.org/ontologies/result#AFR_0001868",
"$asm.pattern": "quantity datum",
"allOf": [
{
"$ref": "http://purl.allotrope.org/json-schemas/adm/core/REC/2023/09/core.schema#/$defs/tQuantityValue"
},
{
"$ref": "http://purl.allotrope.org/json-schemas/qudt/REC/2023/09/units.schema#/$defs/m~1z"
}
]
},
```