build(deps): bump github.com/slack-go/slack from 0.14.0 to 0.15.0

Bumps [github.com/slack-go/slack](https://github.com/slack-go/slack) from 0.14.0 to 0.15.0.
- [Release notes](https://github.com/slack-go/slack/releases)
- [Changelog](https://github.com/slack-go/slack/blob/master/CHANGELOG.md)
- [Commits](slack-go/slack@v0.14.0...v0.15.0)

---
updated-dependencies:
- dependency-name: github.com/slack-go/slack
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/cockroachdb/errors v1.11.3
 	github.com/getsentry/sentry-go v0.29.0
 	github.com/jarcoal/httpmock v1.3.1
-	github.com/slack-go/slack v0.14.0
+	github.com/slack-go/slack v0.15.0
 	github.com/stretchr/testify v1.9.0
 	github.com/xanzy/go-gitlab v0.111.0
 	golang.org/x/sync v0.8.0

go.sum

@@ -98,8 +98,8 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
-github.com/slack-go/slack v0.14.0 h1:6c0UTfbRnvRssZUsZ2qe0Iu07VAMPjRqOa6oX8ewF4k=
-github.com/slack-go/slack v0.14.0/go.mod h1:hlGi5oXA+Gt+yWTPP0plCdRKmjsDxecdHxYQdlMQKOw=
+github.com/slack-go/slack v0.15.0 h1:LE2lj2y9vqqiOf+qIIy0GvEoxgF1N5yLGZffmEZykt0=
+github.com/slack-go/slack v0.15.0/go.mod h1:hlGi5oXA+Gt+yWTPP0plCdRKmjsDxecdHxYQdlMQKOw=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=