fix: errors when querying fields of the acfe_date_range_picker field type

[jasonbahl]

What does this implement/fix? Explain your changes.

This fixes a bug where querying fields of the acfe_date_range_picker field type would return the following error when queried:

"DateTime::createFromFormat(): Argument #2 ($datetime) must be of type string, array given"

Does this close any currently open issues?

closes #163

Any other comments?

When querying a field of the acfe_date_range_picker type:

BEFORE

PHP Errors were being thrown:

AFTER

No more errors:

[coveralls]

Pull Request Test Coverage Report for Build 2120cb25c7e08bdde8c612ee7fc40ee3bdc98c23-PR-166

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• 0 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 62.492%

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Totals
Change from base Build 42bab29b800d1bb012c6d360bc1e6871cff4ca49:	0.06%
Covered Lines:	2031
Relevant Lines:	3250

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💛 - Coveralls