When I attach an image diff with Attach keyword, the report comparator has the height of the shortest image

Hi everybody,

I'm using `allure-robotframework==2.15.2` with `robotframework==7.3.2`
My report is generated with allure-commandline version 2.34.1 `npx --yes allure-commandline generate`

When I attach images (diff, expected, actual) with Attach keyword, then the images displayed in "Show overlay" mode are too short. The bottom of the biggest images is hidden. I have to set the effective size of the `//div[@class="screen-diff__overlay screen-diff__container"]` to show it completely.

For example I've two images with different sizes :

- left img **2109px**
- right img **1907px**
- Comparator size **1926.9px** `//div[@class="screen-diff__overlay screen-diff__container"]`

I expect the comparator height to be at least **2109** instead of **1926**

I don't know if the issue is on allure report or in the listener allure-robotframework

Here is my snipet :
```
${dico}= Create Dictionary expected=data:image/png;base64,${expected_Base64}
... actual=data:image/png;base64,${actual_Base64} diff=data:image/png;base64,${diff_Base64}

${discoAsString} = Convert To String ${dico}
${discoAsStringDoubleQuote} Replace String ${discoAsString} ' "
${dicoAsJson} Convert String To Json ${discoAsStringDoubleQuote}
AllureLibrary.Attach ${discoAsStringDoubleQuote} name=Screenshot diff
... attachment_type=application/vnd.allure.image.diff
```

Thanks for feedback

Reproduziere den image-diff-Anhang mit den bereitgestellten Versionen von allure-robotframework, Robot Framework und allure-commandline unter Verwendung der expected-, actual- und diff-Bilder mit unterschiedlichen Höhen. Ermittle, ob das Verhalten des Comparators zum Python listener oder zum generierten Report gehört, und verifiziere anschließend, dass Show overlay die vollständige Höhe des höchsten Bildes anzeigt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.