Build - close stale issues after 60 days

[BePo65]

This pr solves part of issue #1921 by automatically informing creators of stale issues after 60 days and closing these issues automatically after 2 more weeks.

This github action should help bring down the overwhelming number of open issues, as it seems that only very few people close their issues, when they got answered.

[codecov[bot]]

Codecov Report

Merging #2161 (3babfc7) into dev (e4468a4) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 3babfc7 differs from pull request most recent head 04c2d2f. Consider uploading reports for the commit 04c2d2f to get more accurate results

@@            Coverage Diff            @@
##               dev     #2161   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          183       183           
  Lines         2109      2109           
  Branches       554       554           
=========================================
  Hits          2109      2109           

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