Release 138.0.7260.298 R8

Here is a new release of Supermium 138 ESR. This includes various security updates and general fixes from upstream Chromium 138 ESR, as well as the following:

(#1695) - Solution to remaining browser start failures on account of locale issues; another fallback has been implemented using the en-GB locale.
(#1700) - The v60 tab style now supports split tabs.
(#1686) - Windows 8.0 screensharing issues should now be resolved.
(#1699 and others) - Window borders return to PWAs in cases where they were not visible. General browser window management is improved; there should be no issues with windows randomly stealing focus anymore.