* Normalize datetime values to UTC in blog plugin
Fixes#7705
Normalize datetime values to UTC in blog plugin to handle offset-naive and offset-aware datetimes correctly.
* Import `timezone` from `datetime` in `material/plugins/blog/structure/options.py`.
* Modify `pre_validation` method to set `tzinfo=timezone.utc` for datetime values.
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* Normalize datetime values to UTC in blog plugin
Fixes#7705
+ Move changes to src directory
