Fix transient specs for Time.new

Fix building a new Time instance with naively increased hours by 1:

```ruby
Time.new(..., t.hour + 1, ...)
```

It leads to hours overflowing (becoming greater than 23) and transient failures like the following ones:

```
1)
Time.now Timezone object returned value by #utc_to_local and #local_to_utc methods could be Time instance ERROR
ArgumentError: argument out of range

2)
Time.now Timezone object returned value by #utc_to_local and #local_to_utc methods could be Time subclass instance ERROR
ArgumentError: argument out of range
```

Author: andrykonchin

spec/ruby/core/time/now_spec.rb

@@ -114,7 +114,8 @@ def zone.utc_to_local(time)
         it "could be Time instance" do
           zone = Object.new
           def zone.utc_to_local(t)
-            Time.new(t.year, t.mon, t.day, t.hour + 1, t.min, t.sec, t.utc_offset)
+            time = Time.new(t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset)
+            time + 60 * 60 # + 1 hour
           end
 
           Time.now(in: zone).should be_kind_of(Time)
@@ -124,7 +125,10 @@ def zone.utc_to_local(t)
         it "could be Time subclass instance" do
           zone = Object.new
           def zone.utc_to_local(t)
-            Class.new(Time).new(t.year, t.mon, t.day, t.hour + 1, t.min, t.sec, t.utc_offset)
+            time = Time.new(t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset)
+            time += 60 * 60 # + 1 hour
+
+            Class.new(Time).new(time.year, time.mon, time.day, time.hour, time.min, time.sec, time.utc_offset)
           end
 
           Time.now(in: zone).should be_kind_of(Time)