tasks/users: fix syntax in failed_when

[yogo1212]

this message popped up during execution:

fatal: [host]: FAILED! => {"msg": "The conditional check ''failed' in keyrc and 'getpwnam' not in keyrc.msg' failed. The error was: error while evaluating conditional ('failed' in keyrc and 'getpwnam' not in keyrc.msg): Unable to look up a name or access an attribute in template string ({% if 'failed' in keyrc and 'getpwnam' not in keyrc.msg %} True {% else %} False {% endif %}).\nMake sure your variable name does not contain invalid characters like '-': argument of type 'StrictUndefined' is not iterable"}

kind regards

[antonu17]

Would be very nice to get this PR merged.
@ahelal could you have a chance to take a look at it?

[yogo1212]

@antonu17 @ahelal may i draw your attention to this PR?
#27
iteritems was removed in python3:
https://docs.python.org/3.1/whatsnew/3.0.html#views-and-iterators-instead-of-lists
or in other words: 7 years ago!