Update Slack API dependency and remove workaround for stripping event…

… details from logs #610

##### ISSUE TYPE
 - Feature Pull Request
 - Bug fix Pull Request
 - Docs Pull Request

##### SUMMARY

~⚠️ **NOTE:** For convienence, this PR depends on #603 and needs to be rebased when #603 is merged (it should happen very soon). Actual changes: a6d91f21f25f00d679572e62b45cd2396d571075~

As the upstream fix has been merged (slack-go/slack#1067), this PR updates `slack-go/slack` dependency and removes no longer needed workaround.

See the original issue: #579
See the PR that introduced the workaround: #583

##### TESTING

> **NOTE:** You can also use `pkosiec/botkube:rm-slack-workaround` Docker image for testing. The image was repushed **after** rebase.

1. Checkout this PR
2. Edit `comm_config.yaml` and enable Slack
3. Export needed envs:

```bash
export KUBECONFIG=/Users/$USER/.kube/config
export LOG_LEVEL=info
```

4. Run BotKube locally:

```bash
go run ./cmd/botkube/main.go
```

5. Start Slack huddle and say something, then leave
6. Observe logs still without event details

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/prometheus/client_golang v1.12.2
 	github.com/sha1sum/aws_signing_client v0.0.0-20200229211254-f7815c59d5c1
 	github.com/sirupsen/logrus v1.8.1
-	github.com/slack-go/slack v0.10.3
+	github.com/slack-go/slack v0.10.4-0.20220606002947-9fd6da5aee56
 	github.com/stretchr/testify v1.7.1
 	github.com/vrischmann/envconfig v1.3.0
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c

go.sum

@@ -1004,8 +1004,8 @@ github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrf
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
 github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
 github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
-github.com/slack-go/slack v0.10.3 h1:kKYwlKY73AfSrtAk9UHWCXXfitudkDztNI9GYBviLxw=
-github.com/slack-go/slack v0.10.3/go.mod h1:hlGi5oXA+Gt+yWTPP0plCdRKmjsDxecdHxYQdlMQKOw=
+github.com/slack-go/slack v0.10.4-0.20220606002947-9fd6da5aee56 h1:MH0qxpIb/gmsc/MAbsgMNAK3giE5Zd/6gH8yX/4wsrM=
+github.com/slack-go/slack v0.10.4-0.20220606002947-9fd6da5aee56/go.mod h1:hlGi5oXA+Gt+yWTPP0plCdRKmjsDxecdHxYQdlMQKOw=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
 github.com/smartystreets/assertions v1.0.0 h1:UVQPSSmc3qtTi+zPPkCXvZX9VvW/xT/NsRvKfwY81a8=
 github.com/smartystreets/assertions v1.0.0/go.mod h1:kHHU4qYBaI3q23Pp3VPrmWhuIUrLW/7eUrw0BU5VaoM=

pkg/bot/slack.go

@@ -139,7 +139,7 @@ func (b *SlackBot) Start(ctx context.Context) error {
 				b.log.Errorf("Slack outgoing event error: %+v", ev.Error())
 
 			case *slack.UnmarshallingErrorEvent:
-				b.log.Errorf("Slack unmarshalling error: %+v", b.stripUnmarshallingErrEventDetails(ev.Error()))
+				b.log.Errorf("Slack unmarshalling error: %+v", ev.Error())
 
 			case *slack.RateLimitedError:
 				b.log.Errorf("Slack rate limiting error: %+v", ev.Error())
@@ -151,27 +151,6 @@ func (b *SlackBot) Start(ctx context.Context) error {
 	}
 }
 
-// Temporary workaround until the PR is merged: https://github.com/slack-go/slack/pull/1067
-// There are just two cases when the full event details are concatenated with the error message: https://github.com/slack-go/slack/blob/v0.10.3/websocket_managed_conn.go#L474-L492
-// Also, we need keep the JSON unmarshal error intact: https://github.com/slack-go/slack/blob/v0.10.3/websocket_managed_conn.go#L405
-func (b *SlackBot) stripUnmarshallingErrEventDetails(errMessage string) string {
-	const errMsgSeparator = ": "
-	const prefix = "RTM Error"
-
-	if !strings.HasPrefix(errMessage, prefix) {
-		return errMessage
-	}
-
-	// has prefix, so let's split the message into parts
-	msgParts := strings.Split(errMessage, errMsgSeparator)
-	if len(msgParts) < 3 {
-		// impossible with current version of the dependency
-		return errMessage
-	}
-
-	return strings.Join(msgParts[:2], errMsgSeparator)
-}
-
 // TODO: refactor - handle and send methods should be defined on Bot level
 
 func (sm *slackMessage) HandleMessage(b *SlackBot) error {