Rcpchgrowth

Remove unwanted dependencies
Constrain python version < 3.9 as breaks pytest

Dependency fix

New feature - thrive lines: not yet ready for production

Also adding generate_sds_line function

Patch to fix to prevent fictional child method from return empty objects if beyond reference data.

Breaking change:
Chart return objects will all now return an array and follow the pattern:
`
{
"chart_data": [
"reference_name": {
"male": {
"height": [....],
},
"female": {....}
}
]
}
`

Implements fictional child - as yet untested
Implements percentage median BMI in the Measurement return object with error handling