zoom-us: Update updater script for new Zoom version syntax

Since version 5.8.0 (16) the zoom.us version naming scheme has changed.
Instead of x.y.z (a.b), the new scheme is x.y.z (a).

This commit adapts the awk script to extract versions from the new
naming scheme.

pkgs/applications/networking/instant-messengers/zoom-us/update.sh

@@ -5,6 +5,6 @@ set -eu -o pipefail
 
 version="$(curl -Ls https://zoom.us/download\?os\=linux | \
   pup '.linux-ver-text text{}' | \
-  awk -F'[ ().]' '{printf $2"."$3"."$6"."$7"\n"}')"
+  awk -F'[ ().]' '{printf $2"."$3"."$4"."$6"\n"}')"
 
 update-source-version zoom-us "$version"