Fix const-ness of...

Fix const-ness of ClangCodeModel::Internal::CompletionChunksToTextConverter::inDesiredTextFormat(().

Change-Id: I622b65d7d8fd90d67863282fe85b867acf16b899
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/clangcodemodel/clangcompletionchunkstotextconverter.cpp

@@ -296,7 +296,7 @@ void CompletionChunksToTextConverter::addExtraVerticalSpaceBetweenBraces(
     }
 }
 
-QString CompletionChunksToTextConverter::inDesiredTextFormat(const Utf8String &text)
+QString CompletionChunksToTextConverter::inDesiredTextFormat(const Utf8String &text) const
 {
     if (m_textFormat == TextFormat::Html)
         return text.toString().toHtmlEscaped();