Update alertmanager from 0.28.1 to 0.29.0

[prometheus-rpm-bot]

https://github.com/prometheus/alertmanager/releases/tag/v0.29.0
Release notes:

* [FEATURE] Add incident.io notifier. #4372
* [FEATURE] Add monospace message formatting. #4362
* [FEATURE] Add ability to customize interval for maintenance to run. #4541
* [ENHANCEMENT] Update Jira notifier to support both Jira cloud API v3 and Jira datacenter API v2. #4542
* [ENHANCEMENT] Increase mixin rate intervals for alert `FailedToSendAlerts`. #4206
* [ENHANCEMENT] Make /alertmanager group writable in docker image. #4469
* [BUGFIX] Fix logged notification count on error in notify. #4323
* [BUGFIX] Fix docker image permissions path. #4288
* [BUGFIX] Fix error handling in template rendering for Telegram. #4353
* [BUGFIX] Fix duplicate `other` in error messages for config. #4366
* [BUGFIX] Fix logic that considers an alert reopened in Jira. #4478
* [BUGFIX] Fix Jira issue count #4615