Update fhir.resources dependency

[bwalsh]

We are current with https://github.com/nazrulworld/fhir.resources release 7.1.0 but it has a new release imminent (should be faster)

Release 8 has breaking changes https://github.com/nazrulworld/fhir.resources?tab=readme-ov-file#migration-from-7xx-to-8xx

Additionally, we discovered a shortcoming in 7.1.0.
7.1.0's validator allows the user to assign floats with significant digits to integer fields.

e.g.

patient_dict = {"multipleBirthInteger": 32.9}
patient = Patient.parse_obj(patient_dict)
patient.validate()
# is silently truncated to 
Patient.multipleBirthInteger = 32

After updating, a validation error is raised

    with pytest.raises(ValidationError):
        patient_dict = {"multipleBirthInteger": 32.9}
        patient = Patient.model_validate(patient_dict)