avalonia: update to Avalonia 0.10.7

Update to the latest version of Avalonia to fix various rendering
problems including, shadow issues on macOS, and DPI issues on macOS.

Fixes #408.

Author: mjcheetham

src/shared/Microsoft.Git.CredentialManager.UI.Avalonia/Microsoft.Git.CredentialManager.UI.Avalonia.csproj

@@ -10,9 +10,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Avalonia" Version="0.10.0" />
-    <PackageReference Include="Avalonia.Desktop" Version="0.10.0" />
-    <PackageReference Include="Avalonia.Diagnostics" Version="0.10.0" />
+    <PackageReference Include="Avalonia" Version="0.10.7" />
+    <PackageReference Include="Avalonia.Desktop" Version="0.10.7" />
+    <PackageReference Include="Avalonia.Diagnostics" Version="0.10.7" />
   </ItemGroup>
 
   <ItemGroup>