chore(deps): bump github.com/slack-go/slack from 0.19.0 to 0.20.0 (#73)

Bumps [github.com/slack-go/slack](https://github.com/slack-go/slack) from 0.19.0 to 0.20.0.
- [Release notes](https://github.com/slack-go/slack/releases)
- [Changelog](https://github.com/slack-go/slack/blob/master/CHANGELOG.md)
- [Commits](slack-go/slack@v0.19.0...v0.20.0)

---
updated-dependencies:
- dependency-name: github.com/slack-go/slack
  dependency-version: 0.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/joshdk/go-junit v1.0.0
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.9.4
-	github.com/slack-go/slack v0.19.0
+	github.com/slack-go/slack v0.20.0
 	github.com/stretchr/testify v1.11.1
 	gopkg.in/yaml.v3 v3.0.1
 )

go.sum

@@ -118,8 +118,8 @@ github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0t
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/sirupsen/logrus v1.9.4 h1:TsZE7l11zFCLZnZ+teH4Umoq5BhEIfIzfRDZ1Uzql2w=
 github.com/sirupsen/logrus v1.9.4/go.mod h1:ftWc9WdOfJ0a92nsE2jF5u5ZwH8Bv2zdeOC42RjbV2g=
-github.com/slack-go/slack v0.19.0 h1:J8lL/nGTsIUX53HU8YxZeI3PDkA+sxZsFrI2Dew7h44=
-github.com/slack-go/slack v0.19.0/go.mod h1:K81UmCivcYd/5Jmz8vLBfuyoZ3B4rQC2GHVXHteXiAE=
+github.com/slack-go/slack v0.20.0 h1:gbDdbee8+Z2o+DWx05Spq3GzbrLLleiRwHUKs+hZLSU=
+github.com/slack-go/slack v0.20.0/go.mod h1:K81UmCivcYd/5Jmz8vLBfuyoZ3B4rQC2GHVXHteXiAE=
 github.com/spiffe/go-spiffe/v2 v2.6.0 h1:l+DolpxNWYgruGQVV0xsfeya3CsC7m8iBzDnMpsbLuo=
 github.com/spiffe/go-spiffe/v2 v2.6.0/go.mod h1:gm2SeUoMZEtpnzPNs2Csc0D/gX33k1xIx7lEzqblHEs=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=