astro/google-earth: mark as DEPRECATED

Google Earth needs version 7.1.8 or later required to run[1] since October 2020.

In order to update the port we need _at least_ linux ports for:

• libproxy
• gstreamer
• gstreamer-plugin-base
• libmodman
• orc

But in the end it fails at runtime because our linuxolator glibc is too old
(GLIBC_2.17 vs GLIBC_2.18).

[1] https://support.google.com/earth/thread/43329999/ending-support-for-earlier-versions-of-google-earth?hl=en

PR: 251635