Recognize Joachim Kohlhammer

For his contributions with new features, bug fixes
and QT6 migration.
https://github.com/GoldenCheetah/GoldenCheetah/commits?author=thejockl

src/Gui/AboutDialog.cpp

@@ -152,6 +152,7 @@ ContributorsPage::ContributorsPage(Context *context) : context(context)
     contributors.append("Jan de Visser");
     contributors.append("Jim Ley");
     contributors.append("Jörn Rischmüller");
+    contributors.append("Joachim Kohlhammer");
     contributors.append("Johan Martensson");
     contributors.append("John Ehrlinger");
     contributors.append("Jon Beverley");