fix: Fix indentation when pressing enter with cursor in the indentation

The bug:

    When it's:

    ```
    <space><cursor><space>
    ```

    And you press enter, it will become:

    ```
    <space>
    <space><space><cursor><space>
    ```

    But the expected behavior is:

    ```
    <space>
    <space><cursor><space>
    ```

This commit fixes it.

Author: ouuan

src/internal/QCodeEditor.cpp

@@ -712,6 +712,11 @@ void QCodeEditor::keyPressEvent(QKeyEvent *e)
                 moveCursor(QTextCursor::EndOfBlock);
                 return;
             }
+            else
+            {
+                indentationSpaces = indentationSpaces.left(textCursor().columnNumber());
+            }
+
             insertPlainText("\n" + indentationSpaces);
             return;
         }