Fix `Show JSON` button functionality regression introduced with 0e9f822536

Signed-off-by: Egor Savkin <es@m-labs.hk>

static/js/shop.jsx

@@ -1263,12 +1263,13 @@ class OrderForm extends React.PureComponent {
               placeholder="Additional notes" />
 
           <div className="d-flex flex-column flex-sm-row justify-content-between">
-            <button
+            <input
               className="btn btn-outline-primary w-100 m-0 mb-2 mb-sm-0 me-sm-2"
               style={{'cursor': 'pointer', 'fontWeight': '700'}}
-              onClick={onClickShow}>Show JSON</button>
+              value="Show JSON"
+              onClick={onClickShow} />
 
-            <button className="btn btn-primary w-100 m-0  ms-sm-2" type="submit">{`${isProcessing ? 'Processing ...' : 'Request quote'}`}</button>
+            <input className="btn btn-primary w-100 m-0 ms-sm-2" type="submit" value={`${isProcessing ? 'Processing ...' : 'Request quote'}`} />
           </div>
           {/*This will open an email window. Send the email to make your request.*/}
         </form>