Fix crash while downloading favicon

[ADD-SP]

Fixes #7103

When I'm debugging, I find that it always crashes on this line.

keepassxc/src/gui/IconDownloaderDialog.cpp

Line 188 in 20db504

delete downloader;

So I modified the code.

for (auto*& downloader : m_activeDownloaders) {
     downloader->deleteLater();
     downloader = nullptr;
}

Then I compiled and tested on Windows and the program no longer crashes.

Screenshots

Testing strategy

Type of change

• ✅ Bug fix (non-breaking change that fixes an issue)

[codecov-commenter]

Codecov Report

Merging #7104 (88a5cd5) into develop (20db504) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #7104      +/-   ##
===========================================
- Coverage    63.95%   63.95%   -0.00%     
===========================================
  Files          330      330              
  Lines        41764    41764              
===========================================
- Hits         26708    26706       -2     
- Misses       15056    15058       +2     

Impacted Files	Coverage Δ
src/gui/IconDownloaderDialog.cpp	0.00% <0.00%> (ø)
src/core/Entry.cpp	83.68% <0.00%> (-0.21%)	⬇️

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[droidmonkey]

You can do away with the *& and just keep the deleteLater call. Setting the pointer to nullptr is unnecessary due to the clearing of the list right after this loop.