chore: require go 1.26

[WispHes]

go 1.22.0 -> 1.26.0, to match the rest of the SDKs and the provider.

build.yml and release.yml move off go-version 1.22.0.

.golangci.yml is left alone. It targets 1.21.3, and raising it to 1.26 breaks lint outright: the golangci-lint version pinned in the Makefile, v1.64.8, is the last v1 release and is built with go 1.24, so it refuses a config that targets a newer version. Moving this repo to golangci-lint v2, the way the other SDKs already run it, is a separate change.

Checked locally: go build ./... and go test ./... pass.

[WispHes]

Closing until this repo moves to golangci-lint v2.

The pinned linter, v1.64.8, is the last v1 release and is built with go 1.24. Against a module that declares go 1.26 it cannot typecheck any package at all: "package requires newer Go version go1.26 (application built with go1.24)", and the 50 errors that follow are fallout from that. No change to .golangci.yml gets around it, the go.mod directive alone is enough to break the run.

So the linter upgrade has to land first, then the go 1.26 bump can come back.