[3.x] Fix short array syntax

[zero-24]

Summary of Changes

Make sure we dont use the short array syntax within Joomla 3.x

Testing Instructions

Make sure you can install extensions from URL in php 5.3

Actual result BEFORE applying this Pull Request

Parse error: syntax error, unexpected '[' in administrator\components\com_installer\models\install.php on line 391

Expected result AFTER applying this Pull Request

Works

Documentation Changes Required

none

[alikon]

I have tested this item ✅ successfully on c3390b9

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[richard67]

I have tested this item ✅ successfully on c3390b9

Code review.

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[richard67]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/34802.}

[zero-24]

Merging for now thanks!

[sakiss]

Btw. Is this some type of code style requirement?

[alikon]

no j3 minimum requirement for php is 5.3 where short array syntax is illegal