zoom-us: Make update script get exact version

Their website has changed the format in which they display the version,
into something a bit more sophisticated.

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

@@ -3,6 +3,8 @@
 
 set -eu -o pipefail
 
-version="$(curl -Ls https://zoom.us/download\?os\=linux | pup '.linux-ver-text text{}' | cut -d' ' -f2)"
+version="$(curl -Ls https://zoom.us/download\?os\=linux | \
+  pup '.linux-ver-text text{}' | \
+  awk -F'[ ().]' '{printf $2"."$3"."$6"."$7"\n"}')"
 
 update-source-version zoom-us "$version"