Go 1.26.5 ships and 1.27 RC2 lands for testing

Two releases to grab: Go 1.26.5 is out on the stable track, and 1.27 RC2 is available for anyone willing to run a pre-release in dev or prod and file the bugs that fall out. On the proposals side, the stricter JSON struct-tag checking in the structtag analyzer has been accepted for 1.28, closing off some of the parser footguns highlighted by Trail of Bits earlier in the year. Elsewhere, Excelize is marking ten years with a 2.11.0 release, which is a quietly impressive run for a pure-Go spreadsheet library.