Make link clickable in Yama security error window

[Ashark]

It is inconvenient to copy the link manually every time and pasting it in browser. Better make it clickable in window.

Before:

After:

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Please check if I missed some other place to replace \n with <br>.

I did not used the errorBox.setTextFormat(Qt::MarkdownText);, because it was removed with this commit to support building with Qt < 5.14. I do not know if this version is still needed by anyone, so I decided to use Qt::RichText.

[CLAassistant]

All committers have signed the CLA.

[Ashark]

In INSTALL.md I see that the 5.15 is a minimum supported version:

To build GammaRay you will need at least:

• Qt 5.15 or higher, or Qt 6.3 or higher
  (GammaRay v3.0.0 was the last release to support Qt versions less than 5.15)

So perhaps the current MR can just reenable the Qt::MarkdownText.

[redstrate]

In INSTALL.md I see that the 5.15 is a minimum supported version:

To build GammaRay you will need at least:

• Qt 5.15 or higher, or Qt 6.3 or higher
  (GammaRay v3.0.0 was the last release to support Qt versions less than 5.15)

So perhaps the current MR can just reenable the Qt::MarkdownText.

Correct, we can use MarkdownText here since the minimum Qt was bumped sometime ago

[Ashark]

Correct, we can use MarkdownText here since the minimum Qt was bumped sometime ago

Done.