Update Primer Octicons (GitHub) to v19.15.5 (#372)

Update Primer Octicons (GitHub) to v19.15.5

Author: punker76

README.md

@@ -61,7 +61,7 @@ The same icons are also available for [Avalonia](https://avaloniaui.net/ with th
 | [MingCute Icon](https://github.com/Richard9394/MingCute) | 2.9.6 | 3098 | <a href="https://www.nuget.org/packages/MahApps.Metro.IconPacks.MingCuteIcons/" target="_blank" rel="noopener noreferrer"><img src="https://img.shields.io/nuget/dt/MahApps.Metro.IconPacks.MingCuteIcons.svg?style=flat-square&&label=MingCuteIcons"></a> |
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-| [Primer Octicons (GitHub)](https://github.com/primer/octicons) | 19.15.4 | 657 | <a href="https://www.nuget.org/packages/MahApps.Metro.IconPacks.Octicons/" target="_blank" rel="noopener noreferrer"><img src="https://img.shields.io/nuget/dt/MahApps.Metro.IconPacks.Octicons.svg?style=flat-square&&label=Octicons"></a> |
+| [Primer Octicons (GitHub)](https://github.com/primer/octicons) | 19.15.5 | 657 | <a href="https://www.nuget.org/packages/MahApps.Metro.IconPacks.Octicons/" target="_blank" rel="noopener noreferrer"><img src="https://img.shields.io/nuget/dt/MahApps.Metro.IconPacks.Octicons.svg?style=flat-square&&label=Octicons"></a> |
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