Update phpoffice/phpspreadsheet to v2

[karstennilsen]

• Update dependency
• Replace depricated function setCellValueByColumnAndRow
• htmlHelper->toRichTextObject does not support null anymore, convert null to empty string

Improvement / replacement of #329

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.45%. Comparing base (2c41aae) to head (989c450).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #330   +/-   ##
=======================================
  Coverage   94.45%   94.45%           
=======================================
  Files          36       36           
  Lines         956      956           
=======================================
  Hits          903      903           
  Misses         53       53           

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[curry684]

Looks legit 👍

Keep in mind that this is technically a BC break and so will not be autoupdated without manually changing your dependency.

[curry684]

Turns out your change doesn't break on v1 so we can support both.