upgrade opentelemetry-exporter-zipkin-proto-http protobuf dependency

[shiranbi]

It would be very helpful if the zipkin proto exporter python dependencies would be upgraded
The opentelemetry-proto dependency was already upgraded to "protobuf>=3.19, < 5.0"
but the zipkin exporter is on ~=3.12
making it impossible to upgrade other libraries which require protobuf >= 4.0

[litan1106]

+1

[iwedaz]

Also #3074