Bump github.com/slack-go/slack from 0.19.0 to 0.20.0

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>

Author: dependabot[bot]

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/chromedp/chromedp v0.14.2
 	github.com/coredhcp/coredhcp v0.0.0-20250806070228-f7e98e4e350b
 	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/spf13/pflag v1.0.10
 	github.com/stretchr/testify v1.11.1
 )

go.sum

@@ -82,8 +82,8 @@ github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjR
 github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 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/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
 github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=