Fix empty attributes with i.e. german umlaut in the transport package readme

[Jako]

What does it do?

Change htmlentities to htmlspecialchars

Why is it needed?

In one of my packages I have used a ß in the readme for the transport package. When this transport package is installed, the result the of Workspace/Packages/GetAttribute processor is empty for some reason inside of the Parsedown class in combination with the processor response and the package can't be installed anymore.

How to test

Add a ß in the readme of a transport package.

Related issue(s)/PR(s)

None known

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 21.52%. Comparing base (b1a02c3) to head (bc20c28).
Report is 33 commits behind head on 3.x.

Files with missing lines	Patch %	Lines
...ion/Processors/Workspace/Packages/GetAttribute.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.x   #16713      +/-   ##
============================================
- Coverage     21.53%   21.52%   -0.02%     
+ Complexity    10734    10720      -14     
============================================
  Files           565      565              
  Lines         32540    32533       -7     
============================================
- Hits           7007     7002       -5     
+ Misses        25533    25531       -2     

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