TextEditor: Use override consistently

clang-tidy fixes from modernize-use-override check.

Change-Id: Ie98c08279d7bf01f2705f631500dcabac5ba85d1
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/codeassist/genericproposal.h

@@ -40,7 +40,7 @@ public:
     GenericProposal(int cursorPos, GenericProposalModelPtr model);
     GenericProposal(int cursorPos, const QList<AssistProposalItemInterface *> &items);
 
-    ~GenericProposal();
+    ~GenericProposal() override;
 
     static GenericProposal *createProposal(const AssistInterface *interface,
                                            const QuickFixOperations &quickFixes);