[5.4] update image for "whats new tour"

[heelc29]

Summary of Changes

icon for automated updates was changed in #45669

Testing Instructions

update to Joomla 5.4 (eg. from 5.3)

Actual result BEFORE applying this Pull Request

Expected result AFTER applying this Pull Request

Link to documentations

Please select:

• No documentation changes for docs.joomla.org needed
• No documentation changes for manual.joomla.org needed

[richard67]

I have tested this item ✅ successfully on 393ca6c

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[exlemor]

I have tested this item ✅ successfully on 393ca6c

I have tested this successfully. Updated from 5.3.2 to 5.4.0-alpha4-dev+pr.45836 package.

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[exlemor]

RTC

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[muhme]

✅ Final test before merge: 5.3.3-dev update with nigthly 5.4-dev build – saw old image; with this PR's Joomla_5.4.0-alpha4-dev+pr.45836-Development-Update_Package.zip image with updated icon in different browser seen (first browser is showing persistent cached old image)

• Note: Image is slightly increased from 774x281 to 826x300, but I assume it doesn't matter as the displayed size is variable and smaller depending on the size of the browser window

[muhme]

Thank you @heelc29 for your contribution. Thank you @richard67 and @exlemor for testing.