go/build: remove nonexistent package from TestDependencies

go/build: remove nonexistent package from TestDependencies

crypto/internal/boring/fips140tls is not a package in the Go standard
library, so it should not be listed in TestDependencies.

Change-Id: I6476da397b0204fcbd0a11b27a29112fca4b6023
Reviewed-on: https://go-review.googlesource.com/c/go/+/636415
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Auto-Submit: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>