Update GitLogTests to use contains for branch expectations.

Author: maoyama

GitClientTests/GitLogTests.swift

@@ -16,7 +16,8 @@ struct GitLogTests {
         #expect(commits.last!.hash == "f9635d9f3b39534e84f183555274867199af76a3")
         #expect(commits.last!.title == "Initial Commit")
         #expect(commits.first!.abbreviatedParentHashes == ["cfae930", "e129fc7"])
-        #expect(commits.first!.branches == ["HEAD -> main", "origin/main", "origin/HEAD"])
+        #expect(commits.first!.branches.contains("origin/main"))
+        #expect(commits.first!.branches.contains("origin/HEAD"))
         #expect(commits.first!.tags == ["v0.2.0"])
         #expect(commits.count == 29)
     }