internal/postgres: stop writing to licenses.module_path and licenses.version
internal/postgres: stop writing to licenses.module_path and licenses.version

In a later CL, licenses.module_path and licenses.version will be
dropped.

For golang/go#39629

Change-Id: I7de03b66686e04128c761f477130eb98571a8cd2
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/272087
Trust: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
Run-TryBot: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
TryBot-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite