ci: Wait for npm before dispatching, and skip releases for workflow-only changes

.github/workflows/publish-to-npm.yaml

@@ -3,6 +3,9 @@ name: Publish to npm
 on:
   push:
     branches: [ master ]
+    # A merge that only changes workflows does not change the package, so it is not released
+    paths-ignore:
+      - '.github/**'
 
 # Never run two publishes at once; a second merge waits for the first to finish
 concurrency:
@@ -51,6 +54,21 @@ jobs:
       run: npm publish
       env:
         NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN2 }}
+    # npm may take several minutes to make a new version available; downstream repositories install @latest
+    # as soon as they are dispatched, so wait until the new version can be fetched before dispatching
+    - name: Wait for the new version on npm
+      run: |
+        version=$(node -p "require('./package.json').version")
+        for i in $(seq 1 60); do
+          if curl -sf -o /dev/null "https://registry.npmjs.org/@openactive%2fdata-model-validator/$version?nocache=$(date +%s)"; then
+            echo "$version is available on npm"
+            exit 0
+          fi
+          echo "Attempt $i: $version not yet available, waiting"
+          sleep 30
+        done
+        echo "$version was not available on npm within 30 minutes"
+        exit 1
 
   dispatch:
     needs: publish