Fix generation of UTC times in spec

What does this MR do and why?

Ruby 3.0 allowed Time.utc('2022-01-02') even though it wasn't officially documented, but Ruby 3.1+ introduces stricter checking (https://github.com/ruby/ruby/blob/v3_1_4/NEWS.md). This commit fixes one test that was passing in a string instead of integers.

• Time

  • Time.new now accepts optional in: keyword argument for the timezone, as well as Time.at and Time.now, so that is now you can omit minor arguments to Time.new. Feature 17485

    Time.new(2021, 12, 25, in: "+07:00")
    #=> 2021-12-25 00:00:00 +0700

    At the same time, time component strings are converted to integers more strictly now.

    Time.new(2021, 12, 25, "+07:30")
    #=> invalid value for Integer(): "+07:30" (ArgumentError)

    Ruby 3.0 or earlier returned probably unexpected result 2021-12-25 07:00:00, not 2021-12-25 07:30:00 nor 2021-12-25 00:00:00 +07:30.

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