Bump slack-sdk[optional] from 3.19.2 to 3.19.3 in /server

Bumps [slack-sdk[optional]](https://github.com/slackapi/python-slack-sdk) from 3.19.2 to 3.19.3.
- [Release notes](https://github.com/slackapi/python-slack-sdk/releases)
- [Changelog](https://github.com/slackapi/python-slack-sdk/blob/main/docs-v2/changelog.html)
- [Commits](slackapi/python-slack-sdk@v3.19.2...v3.19.3)

---
updated-dependencies:
- dependency-name: slack-sdk[optional]
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

server/requirements.txt

@@ -24,7 +24,7 @@ aiomcache==v0.7.0
 uvloop==0.17.0
 bootstrapped==0.0.2
 tqdm==4.64.1
-slack_sdk[optional]==3.19.2
+slack_sdk[optional]==3.19.3
 gcloud-aio-kms==4.0.0
 # gcloud-aio-kms does not pin the exact versions of the following packages
 gcloud-aio-auth==4.0.1