lock prometheus-client as 0.9.x so as to keep compatibility

[sat0yu]

The latest version (v0.10.0) of prometheus-client includes a breaking change.

- def counter(name, docstring, base_labels = {})
+ def counter(name, docstring:, labels: [], preset_labels: {}, store_settings: {})

1: from /vendor/bundle/2.5.3/gems/grpc_prometheus-0.1.0/lib/grpc_prometheus/server_metrics.rb:12:in `initialize'
/vendor/bundle/2.5.3/gems/prometheus-client-0.10.0/lib/prometheus/client/registry.rb:40:in `counter': wrong number of arguments (given 2, expected 1; required keyword: docstring) (ArgumentError)

However, v0.10.0 is yet to be officially released yet.
So, In order to avoid exceptions there, could it be possible for this gem to fix the dependency's version until gaining the compatibility?

[yuya-takeyama]

I apologize for not being responsive.
This repository is no longer maintained and will be closed.