Release 0.28.1

[grobinson-grafana]

• [ENHANCEMENT] Improved performance of inhibition rules when using Equal labels. replace Resolved with ResolvedAt to reduce amount call to time.Now() #4119
• [ENHANCEMENT] Improve the documentation on escaping in UTF-8 matchers. Improve the documentation on escaping in UTF-8 matchers #4157
• [ENHANCEMENT] Update alertmanager_config_hash metric help to document the hash is not cryptographically strong. Document that the hash exposed in alertmanager_config_hash is not cryptographically strong #4210
• [BUGFIX] Fix panic in amtool when using --verbose. amtool: fix panic if --verbose is in used. #4218
• [BUGFIX] Fix templating of channel field for Rocket.Chat. Fix rocketchat channel templating #4220
• [BUGFIX] Fix rocketchat_configs written as rocket_configs in docs. Fixed rocketchat_configs docs #4217
• [BUGFIX] Fix usage for --enable-feature flag. Fix descriptions for --enable-feature #4214
• [BUGFIX] Trim whitespace from OpsGenie API Key. opsgenie : trim space for api key file #4195
• [BUGFIX] Fix Jira project template not rendered when searching for existing issues. Render Jira project template when searching for existing issues #4291
• [BUGFIX] Fix subtle bug in JSON/YAML encoding of inhibition rules that would cause Equal labels to be omitted. Fix subtle bug in JSON/YAML encoding of inhibition rules #4292
• [BUGFIX] Fix header for slack_configs in docs. fix:(alertmanager/docs): header for slack config #4247
• [BUGFIX] Fix weight and wrap of Microsoft Teams notifications. Fix format issues of msteams adapter card #4222
• [BUGFIX] Fix format of YAML examples in configuration.md. Fixed formatting error #4207

[grobinson-grafana]

Looking at how @SuperQ did this, he created a PR for main with the updated CHANGELOG.md, and then tagged that merge commit (https://github.com/prometheus/alertmanager/tree/v0.28.0) as v0.28.0. I was going to do the same here, unless I should do something else?

[gotjosh]

I think you also need to update: https://github.com/prometheus/alertmanager/blob/main/VERSION