Update junos_exporter from 0.12.3 to 0.12.5

[prometheus-rpm-bot]

https://github.com/czerwonk/junos_exporter/releases/tag/0.12.5
Release notes:

## What's Changed
* feat: add l2vpn metrics by @Gaste8 in https://github.com/czerwonk/junos_exporter/pull/248
* fix: add flag for L2VPN in main.go by @Gaste8 in https://github.com/czerwonk/junos_exporter/pull/254
* expose configured MTU on physical and virtual interfaces by @maxiestudies in https://github.com/czerwonk/junos_exporter/pull/256
* Added macsec feature  by @surprise30 in https://github.com/czerwonk/junos_exporter/pull/261
* Helm: chart fixes and improvements by @crabique in https://github.com/czerwonk/junos_exporter/pull/259

## New Contributors
* @maxiestudies made their first contribution in https://github.com/czerwonk/junos_exporter/pull/256
* @surprise30 made their first contribution in https://github.com/czerwonk/junos_exporter/pull/261
* @crabique made their first contribution in https://github.com/czerwonk/junos_exporter/pull/259

**Full Changelog**: https://github.com/czerwonk/junos_exporter/compare/0.12.4...0.12.5