prometheus client_golang dependency is out of date

[ackratos]

our tendermint project depends on https://github.com/deathowl/go-metrics-prometheus (another one depends on go-metrics rather than go-kit to generate metrics) which relies on latest prometheus client_golang https://github.com/prometheus/client_golang. This caused conflict with tendermint dependency.

As the comment in Gopkg.toml file looks wrong, we should remove client_golang constraint.

# Haven't made a release since 2016.
[[constraint]]
  name = "github.com/prometheus/client_golang"
  revision = "ae27198cdd90bf12cd134ad79d1366a6cf49f632"

Tendermint version (use tendermint version or git rev-parse --verify HEAD if installed from source):
1944d85

ABCI app (name for built-in, URL for self-written if it's publicly available):

Environment:

• OS (e.g. from /etc/os-release):
• Install tools:
• Others:

What happened:

What you expected to happen:

Have you tried the latest version: yes/no

How to reproduce it (as minimally and precisely as possible):

Logs (paste a small part showing an error (< 10 lines) or link a pastebin, gist, etc. containing more of the log file):

Config (you can paste only the changes you've made):

node command runtime flags:

/dump_consensus_state output for consensus bugs

Anything else we need to know:

[ackratos]

PR #2799 is raised for fixing this issue

[melekes]

PR with a fix/feature was merged to develop. Will be shipped with 0.26.2 (check the changelog).