tools: fix reference to no longer existing install-deps.sh
tools: fix reference to no longer existing install-deps.sh

install-deps is now a Python script, update the message to make user's
life easier.

BUG=None
TEST=./tools/presubmit

Change-Id: Id1eca4f5b1fb0066574b6b7c381c908e65d919e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3536892
Reviewed-by: Dennis Kempin <cd09796fb571bec2782819dbfd33307f65b1c778@google.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Dmitry Torokhov <10a8c465cefc9bdd6c925e26964d23c90f1141cc@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm