COMP: Update ctkPythonConsole to remove use of deprecated QString API

Fixes the following warning:

```
/path/to/CTK/Libs/Scripting/Python/Widgets/ctkPythonConsole.cpp: In member function ‘virtual void ctkPythonConsoleCompleter::updateCompletionModel(const QString&)’:
/path/to/CTK/Libs/Scripting/Python/Widgets/ctkPythonConsole.cpp:459:56: warning: ‘qsizetype QString::count() const’ is deprecated: Use size() or length() instead. [-Wdeprecated-declarations]
  459 |     if (dotCount == 0 || completion.at(completion.count() - 1) == '.')
      |                                        ~~~~~~~~~~~~~~~~^~
```

Author: jcfr

Libs/Scripting/Python/Widgets/ctkPythonConsole.cpp

@@ -456,7 +456,11 @@ void ctkPythonConsoleCompleter::updateCompletionModel(const QString& completion)
     // choices matches one of the preference list, it will be selected.
     QModelIndex preferredIndex = this->completionModel()->index(0, 0);
     int dotCount = completion.count('.');
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
+    if (dotCount == 0 || completion.at(completion.size() - 1) == '.')
+#else
     if (dotCount == 0 || completion.at(completion.count() - 1) == '.')
+#endif
     {
       foreach(const QString& pref, this->AutocompletePreferenceList)
       {