update regex

.github/workflows/publish-readme.sh

@@ -1,13 +1,15 @@
 #!/bin/bash
 
 get_version() {
-  grep -E '^ \* Version:\s+(\d+\.\d+\.\d+)$' src/wordlift.php | grep -oE '(\d+\.\d+\.\d+)$'
+  # This regex is crafted to work on ubuntu:22.04 which is the GH runner.
+  grep -P '^ \* Version:\s+(\d+\.\d+\.\d+)$' src/wordlift.php | grep -oP '(\d+\.\d+\.\d+)$'
 }
 
 if [[ 'src/readme.txt' == "$(git diff HEAD^ HEAD --name-only)" || "$GITHUB_EVENT_NAME" == "workflow_dispatch" ]]; then
   echo 'readme.txt has been updated, pushing...'
 
   version="$(get_version)"
+  echo "** Using version $version"
   sed -i "s|^Stable tag: .*$|Stable tag: $version|g" src/readme.txt
 
   echo "** readme.txt new contents: "