build(deps): bump slack-sdk from 3.38.0 to 3.39.0 in /block-kit (#19)

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Author: dependabot[bot]

block-kit/requirements.txt

@@ -1,4 +1,4 @@
 mypy==1.18.2
 pytest==9.0.1
 ruff==0.14.5
-slack_sdk==3.38.0
+slack_sdk==3.39.0