Go directive in go.mod is invalid

[mauri870]

According to https://go.dev/issues/62278 a concrete go version has to include the
patch number or an additional toolchain directive. The project declares the version
as 1.22 which is invalid and will result in an error.

GOTOOLCHAIN="go1.21+auto" go1.22.4 mod tidy
go: downloading go1.22 (linux/amd64)
go: download go1.22 for linux/amd64: toolchain not available

We should change it to go 1.22.0 as this is the first actual release of go 1.22. Another option is to specify a toolchain directive:

go 1.22
toolchain go1.22.0