all: update golang.org/x dependencies

Updating x/tools to a newer version teaches it about export data
version 5, and in turn fixes test failures that happen at Go tip
and with Go 1.27.2:

$ go version
go version go1.27.2 darwin/arm64
$ go test ./...
[...] failed: can't fix source: [...] cannot decode "google.golang.org/open2opaque/internal/fix/testdata/proto2test_go_proto", export data version 5 is greater than maximum supported version 4 [...]

For golang/go#81188.

[git-generate]
go get golang.org/x/{tools,sync,exp}
go mod tidy

PiperOrigin-RevId: 999310894
Change-Id: I52fca1164762dcd09792c9ff8f6ebfee3a5bc1f8