Using date_default_timezone_set() and similar isn't allowed.

[matt-bernhardt]

Recent runs of PHPCS on Travis (including on #170) have returned the following:

FILE: ...ordpress/src/wp-content/themes/MITlibraries-parent/lib/hours.php
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FOUND 1 ERROR AFFECTING 1 LINE
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 27 | ERROR | Using date_default_timezone_set() and similar isn't
    |       | allowed, instead use WP internal timezone support.
    |       | (WordPress.VIP.TimezoneChange.timezone_change)
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Fixing this will involve setting the default timezone at the server level, so it may take a bit of coordination. There may also be a better way of declaring such a timezone as the default - will research.