Go 1.26 is now the "stable" SLE BCI Go development container

[dirkmueller]

A bit later than usual, but we rolled over :stable to 1.26 Go. Go 1.25 is still maintained until Go 1.27 comes around, and is available either under :oldstable or :1.25 tags, respectively. Please note that we also introduced a :1.26-sles15 tag that will allow you to pin the SUSE Linux Enterprise Server 15 build of SUSE's Go, which is important for when we roll over to SUSE Linux Enterprise Server 16 with Go 1.27.