Support info metric type

[tykling]

Hello,

Thank you for a great product, I use it on all my servers and VMs.

When trying to use https://github.com/prometheus/client_python#info metric type in an exporter behind expexp I get this error:

Mar 9 06:51:35 blackbox3 supervisord[64200]: exporter_exporter time="2023-03-09T06:51:35Z" level=error msg="Verification for module 'dnsexp' failed: Failed to decode metrics from proxied server: text format parsing error in line 20: unknown metric type \"info\""

I think it will be the same issue for https://github.com/prometheus/client_python#enum type metrics.

It would be nice to support both types.

[tcolgate]

I'll have a look to see if there are any updates to the client_go package that would help. In the mean time, you could turn off metrics verification in the config for that module.

[duck-rh]

Quack,

Got the same problem with the dovecot native metrics:

# HELP dovecot_build Dovecot build information--:--:-- --:--:-- --:--:--     0
# TYPE dovecot_build info
dovecot_build_info{version="2.3.19.1",revision="9b53102964"} 1

Thanks for the workaround.
\_o<