build(deps): update packaging requirement from <26 to <27 (#88)

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

Author: dependabot[bot]

requirements.txt

@@ -1,2 +1,2 @@
 slack_bolt>=1.18.0,<2
-packaging<26
+packaging<27