Make data array variable type within `Report` more precise

[fritzmg]

Just a minor issue that PHP stan found in our project:

Error: Parameter #1 $data of class Nelmio\SecurityBundle\ContentSecurityPolicy\Violation\Report constructor expects array<string, string>, array<string, int|string> given.
 ------ ---------------------------------------------------------------------- 
  Line   core-bundle/tests/EventListener/CspReportListenerTest.php             
 ------ ---------------------------------------------------------------------- 
  47     Parameter #1 $data of class                                           
         Nelmio\SecurityBundle\ContentSecurityPolicy\Violation\Report          
         constructor expects array<string, string>, array<string, int|string>  
         given.                                                                
 ------ ---------------------------------------------------------------------- 

The JSON data sent by the browser can in fact also have integers for the following keys:

• column-number
• line-number
• status-code

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (da7cc88) 96.93% compared to head (f7a2bde) 96.93%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #332 +/- ## ========================================= Coverage 96.93% 96.93% Complexity 429 429 ========================================= Files 52 52 Lines 1923 1923 ========================================= Hits 1864 1864 Misses 59 59 ```

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[fritzmg]

Not sure how to fix the other issues reported by PHP stan. These methods do in fact only ever return a string or null.