sublime3{,-dev}: fix updateScript

The HTML page changed and the update script was no longer finding the latest version.
I changed it to query for the latest version using dedicated URL:

https://forum.sublimetext.com/t/fixed-download-url-for-latest-version/23763/7

Also terminated the update sooner if we detect no update available.
update-source-version handles that normally but we are cleaning the version
so that we can update both platforms at the same time.

pkgs/applications/editors/sublime/3/common.nix

@@ -13,7 +13,7 @@ let
   primaryBinary = "sublime_text";
   primaryBinaryAliases = [ "subl" "sublime" "sublime3" ];
   downloadUrl = "https://download.sublimetext.com/sublime_text_3_build_${buildVersion}_${arch}.tar.bz2";
-  versionUrl = "https://www.sublimetext.com/${if dev then "3dev" else "3"}";
+  versionUrl = "https://download.sublimetext.com/latest/${if dev then "dev" else "stable"}";
   versionFile = builtins.toString ./packages.nix;
   archSha256 =
     if stdenv.hostPlatform.system == "i686-linux" then
@@ -133,7 +133,12 @@ in stdenv.mkDerivation (rec {
     set -o errexit
     PATH=${stdenv.lib.makeBinPath [ common-updater-scripts curl gnugrep ]}
 
-    latestVersion=$(curl -s ${versionUrl} | grep -Po '(?<=<p class="latest"><i>Version:</i> Build )([0-9]+)')
+    latestVersion=$(curl -s ${versionUrl})
+
+    if [[ "${buildVersion}" = "$latestVersion" ]]; then
+        echo "The new version same as the old version."
+        exit 0
+    fi
 
     for platform in ${stdenv.lib.concatStringsSep " " meta.platforms}; do
         # The script will not perform an update when the version attribute is up to date from previous platform run