internal/lsp: update go.mod for next version
internal/lsp: update go.mod for next version

Change-Id: Ic2e437f7daec94f648ba1a13e99a9ada462cdf49
Reviewed-on: https://go-review.googlesource.com/c/tools/+/194897
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools