Fix style issues pointed out by PHP_CodeSniffer

Fix the following errors from PHP_CodeSniffer with the help og phpcbf:

FILE: /home/ao2/Proj/Tweeper/tweeper/tweeper.php
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FOUND 3 ERRORS AFFECTING 3 LINES
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  54 | ERROR | [x] Short array syntax must be used to define arrays
  65 | ERROR | [x] Short array syntax must be used to define arrays
 124 | ERROR | [x] Short array syntax must be used to define arrays
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PHPCBF CAN FIX THE 3 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /home/ao2/Proj/Tweeper/tweeper/src/Tweeper.php
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FOUND 15 ERRORS AFFECTING 12 LINES
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 162 | ERROR | [x] Short array syntax must be used to define arrays
 169 | ERROR | [x] Short array syntax must be used to define arrays
 183 | ERROR | [x] Short array syntax must be used to define arrays
 212 | ERROR | [x] Short array syntax must be used to define arrays
 313 | ERROR | [x] Short array syntax must be used to define arrays
 313 | ERROR | [x] Short array syntax must be used to define arrays
 315 | ERROR | [x] Short array syntax must be used to define arrays
 378 | ERROR | [x] Short array syntax must be used to define arrays
 378 | ERROR | [x] Short array syntax must be used to define arrays
 437 | ERROR | [x] Short array syntax must be used to define arrays
 466 | ERROR | [x] Short array syntax must be used to define arrays
 466 | ERROR | [x] Short array syntax must be used to define arrays
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PHPCBF CAN FIX THE 12 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Time: 273ms; Memory: 10MB