fix(test-suite): the output of the tests was affected by the user's timezone

Author: zah

test/fixtures/more_types_output.txt

@@ -1 +1 @@
-[1.5, {:a=>1, :b=>2}, 1..3, #<Set: {1, 2, 3}>, 1970-01-01 00:00:00 +0000, /ab/, #<struct Point x=5, y=6>, #<OpenStruct foo=7, bar=8>]
+[1.5, {:a=>1, :b=>2}, 1..3, #<Set: {1, 2, 3}>, 1970-01-01 00:00:00 UTC, /ab/, #<struct Point x=5, y=6>, #<OpenStruct foo=7, bar=8>]

test/fixtures/more_types_trace.json

@@ -527,7 +527,7 @@
   {
     "Event": {
       "kind": 0,
-      "content": "1.5\n{:a=>1, :b=>2}\n1..3\n#<Set: {1, 2, 3}>\n1970-01-01 00:00:00 +0000\n/ab/\n#<struct Point x=5, y=6>\n#<OpenStruct foo=7, bar=8>",
+      "content": "1.5\n{:a=>1, :b=>2}\n1..3\n#<Set: {1, 2, 3}>\n1970-01-01 00:00:00 UTC\n/ab/\n#<struct Point x=5, y=6>\n#<OpenStruct foo=7, bar=8>",
       "metadata": ""
     }
   }

test/programs/more_types.rb

@@ -20,7 +20,7 @@ def inspect = "#<Set: {#{@arr.join(', ')}}>"
   {a: 1, b: 2},
   (1..3),
   Set.new([1, 2, 3]),
-  Time.at(0),
+  Time.at(0).utc,
   /ab/,
   Point.new(5, 6),
   OpenStruct.new(foo: 7, bar: 8)