Revert "[Dates] Make test more robust against non-UTC timezones (JuliaLang#55829) (#184)" (#188)

This reverts commit a911d00.

Author: d-netto

stdlib/Dates/test/types.jl

@@ -257,11 +257,7 @@ end
 end
 
 @testset "issue #31524" begin
-    # Ensure the result doesn't depend on local timezone, especially on macOS
-    # where an extra internal call to `mktime` is affected by timezone settings.
-    dt1 = withenv("TZ" => "UTC") do
-        Libc.strptime("%Y-%m-%dT%H:%M:%SZ", "2018-11-16T10:26:14Z")
-    end
+    dt1 = Libc.strptime("%Y-%M-%dT%H:%M:%SZ", "2018-11-16T10:26:14Z")
     dt2 = Libc.TmStruct(14, 30, 5, 10, 1, 99, 3, 40, 0)
 
     time = Time(dt1)