Bump @slack/web-api from 7.8.0 to 7.9.0 (#180)

Bumps [@slack/web-api](https://github.com/slackapi/node-slack-sdk) from 7.8.0 to 7.9.0.
- [Release notes](https://github.com/slackapi/node-slack-sdk/releases)
- [Commits](https://github.com/slackapi/node-slack-sdk/compare/@slack/web-api@7.8.0...@slack/web-api@7.9.0)

---
updated-dependencies:
- dependency-name: "@slack/web-api"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package-lock.json

@@ -10,7 +10,7 @@
   },
   "dependencies": {
     "@probot/adapter-aws-lambda-serverless": "^4.0.3",
-    "@slack/web-api": "^7.8.0",
+    "@slack/web-api": "^7.9.0",
     "probot": "^13.4.4"
   },
   "repository": "github:emergency-pull-request-probot-app",