Model output schemas with £ signs have incorrect encoding

## Bug Report

### Steps to Reproduce:
1. create a model that uses the csv schema importer to set the out dataset's schema
2. in the format_code entry of the schema set it as ",|.|0|£||1" for any float or integer field (this is interpreted as an amount in GBP by the UI)
3. run the model via the TRAC UI
4. get the output dataset via the TRAC API.

### Expected Result:
The schema will be returned via the API as defined in the CSV

### Actual Result:
The schema is returned with the wrong encoding to the £ sign. e.g. £

### Environment:
TRAC UI : 0.5.24",
local TRAC sandbox TRAC: 0.5.24

Defined output schema:


Formatted table using schema from API:


Start with the CSV schema importer and follow the output dataset schema through the TRAC UI execution path to the TRAC API response. Reproduce the issue using the format_code value ",|.|0|£||1" for a numeric field, then compare the API schema with the CSV definition. Done means the £ sign is returned with the correct encoding.

Written by the indexing model from the issue text.