Add ability to disable "generated" timestamp

[licaon-kter]

While not all apps are built reproducible in F-Droid, we continuously test older versions on https://verification.f-droid.org/ and would like more and more apps to become repro

The res/raw/license file that is generated by this lib contains a timestamp which is unique for each build. This makes the build not reproducible.

Would it be possible to add an option to either remove the property / set it to null / hardcode a value? Here: https://github.com/jk1/Gradle-License-Report/blob/v2.9/src/main/groovy/com/github/jk1/license/render/TextReportRenderer.groovy#L54

eg. the other lib has this off by default: mikepenz/AboutLibraries#1056

ref: https://verification.f-droid.org/org.kde.kdeconnect_tp_13304.apk.diffoscope.html#res-raw-license

ref: https://invent.kde.org/network/kdeconnect-android/-/blob/v1.33.4/gradle/libs.versions.toml?ref_type=tags#L14