type "voltage_range" unnecessary

[untzag]

The type "voltage_range" doesn't need to be a defined type, since it's just an array, as far as I know. Why don't use just use an array?

[untzag]

This was brought to my attention by yaq-project/yaq-fyi#94

[ksunden]

In general I think having a shorthand name for a type is not bad... however, avro only supports named types for records, fixed length, and enum types. And this is none of those.

https://avro.apache.org/docs/1.11.1/specification/#names