Add compatibility testing for Go 1.18

[MrAlias]

Match our versioning policy and test the latest version of Go (1.18).

Initial attempts show this will likely need to include fixes to code or the CI system to resolve issues. For example this error:

go test -timeout 60s -short ./instrumentation/github.com/astaxie/beego/otelbeego/...
go: downloading github.com/astaxie/beego v1.12.3
go: downloading go.opentelemetry.io/otel/metric v0.27.0
go: downloading github.com/felixge/httpsnoop v1.0.2
go: downloading go.opentelemetry.io/otel/internal/metric v0.27.0
go: downloading gopkg.in/yaml.v2 v2.2.8
go: downloading github.com/hashicorp/golang-lru v0.5.4
go: downloading github.com/prometheus/client_golang v1.7.0
go: downloading golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
go: downloading github.com/shiena/ansicolor v0.0.0-20151119151921-a422bbe96644
go: downloading github.com/prometheus/client_model v0.2.0
go: downloading github.com/prometheus/common v0.10.0
go: downloading github.com/beorn7/perks v1.0.1
go: downloading github.com/cespare/xxhash/v2 v2.1.1
go: downloading github.com/golang/protobuf v1.4.2
go: downloading github.com/prometheus/procfs v0.1.3
go: downloading github.com/matttproud/golang_protobuf_extensions v1.0.1
go: downloading google.golang.org/protobuf v1.25.0
go: downloading golang.org/x/net v0.0.0-20200707034311-ab3426394381
go: downloading golang.org/x/sys v0.0.0-20200803210538-64077c9b5642
go: downloading golang.org/x/text v0.3.3
# golang.org/x/sys/unix
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/syscall_darwin.1_13.go:29:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.1_13.go:27:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.1_13.go:40:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:28:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:43:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:59:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:75:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:90:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:105:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:121:3: //go:linkname must refer to declared function or variable
Error: /Users/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20200803210538-64077c9b5642/unix/zsyscall_darwin_amd64.go:121:3: too many errors
FAIL	go.opentelemetry.io/contrib/instrumentation/github.com/astaxie/beego/otelbeego [build failed]
?   	go.opentelemetry.io/contrib/instrumentation/github.com/astaxie/beego/otelbeego/internal	[no test files]
FAIL

[MrAlias]

Related to quoted error: golang/go#49219

Sounds like upgrading golang.org/x/sys should resolve it.