fix: bug with file requirements not changing on delete of file (#2417)

* fix: resolve bug where deleting a file didn't remove label

- Reinstate the `merge` which updates state directly
- This isn't best practice but does show how the bug started happening

* refactor: update the remove method to avoid direct state update

- Create a clone of fileList before removing the file
- Remove the file and update state with the setter

editor.planx.uk/src/@planx/components/FileUploadAndLabel/Public.tsx

@@ -240,11 +240,12 @@ function Component(props: Props) {
                       ),
                     );
                     setFileUploadStatus(`${slot.file.path} was deleted`);
-                    removeSlots(
+                    const updatedFileList = removeSlots(
                       getTagsForSlot(slot.id, fileList),
                       slot,
                       fileList,
                     );
+                    setFileList(updatedFileList);
                   }}
                 />
               );