Fix asking to install Python

The dialog asking users to install python is borked since the last refactor, this
commit fixes it.

src/base/utils/foreignapps.h

@@ -42,6 +42,7 @@ namespace Utils
             using Version = Utils::Version<quint8, 3, 1>;
 
             bool isValid() const;
+            bool isSupportedVersion() const;
 
             QString executableName;
             Version version;