[Repo Assist] test: add SideEffects module to TaskSeq.FirstLastDefault.Tests.fs#403

dsyme merged 2 commits intomainfsprojects/FSharp.Control.TaskSeq:mainfrom

repo-assist/test-firstlastdefault-sideeffects-20260422-ae6f0ce0cffc314ffsprojects/FSharp.Control.TaskSeq:repo-assist/test-firstlastdefault-sideeffects-20260422-ae6f0ce0cffc314fCopy head branch name to clipboard