Decode: don't panic when date time is missing timezone

[RiyaJohn]

Issue: #596

Explanation of what this pull request does.
Fixes the issue of throwing unexpected panic
Returns more meaningful error for the user

More detailed description of the decisions being made and the reasons why (if the patch is non-trivial).

[pelletier]

Thank you for submitting a patch! We purposefully do not use regexps in this library because they are redundant (we're already writing a validating state machine), slower, and incurs memory allocation. We need a different solution for this problem.

[RiyaJohn]

Thank you for submitting a patch! We purposefully do not use regexps in this library because they are redundant (we're already writing a validating state machine), slower, and incurs memory allocation. We need a different solution for this problem.

Got it, will work on a different solution

[RiyaJohn]

@pelletier Made changes to not use regexp

[pelletier]

Thanks for the patch! Removed a debug statement and added a test to double check the reported issue was fixed.

[RiyaJohn]

Thanks @pelletier, will be great if you could add the hactoberfest-accepted label just in case hactoberfest topic is not there for repo

[pelletier]

@RiyaJohn added, but there is the hacktoberfest topic on the repo.