Deprecation warnings about datetime.utcnow and datetime.utcfromtimestamp

[Marat Sharafutdinov]

Method datetime.utcnow is deprecated since version 3.12:

DeprecationWarning: datetime.datetime.utcnow() 
is deprecated and scheduled for removal in a future version. 
Instead, Use timezone-aware objects to represent datetimes in UTC: 
datetime.datetime.now(datetime.UTC).

Method datetime.utcfromtimestamp is deprecated since version 3.12:

DeprecationWarning: datetime.datetime.utcfromtimestamp() 
is deprecated and scheduled for removal in a future version. 
Use timezone-aware objects to represent datetimes in UTC: 
datetime.datetime.fromtimestamp(timestamp, datetime.UTC).