Serialize request-converter npm publishes

Release branches are tagged within seconds of each other and each
release publishes the same npm package. npm rewrites the whole
packument on publish, so the later run fails with "409 Conflict -
Failed to save packument". 8.19.25 lost that race against 9.5.1 and
published nothing.

A concurrency group serializes the runs. "queue: max" is required
because the default single pending slot cancels an already-pending run
when a third arrives, which would silently drop a publish in a
three-release cluster.

Author: flobernd

.github/workflows/request-converter-npm-publish.yml

@@ -18,6 +18,15 @@ permissions:
   contents: read
   id-token: write
 
+# npm rewrites the whole packument on publish, so two releases publishing this package
+# seconds apart make the loser fail with E409. Release branches are tagged together, so
+# the publishes have to be serialized. "queue: max" holds a later run rather than
+# cancelling it, which the default single pending slot would do.
+concurrency:
+  group: request-converter-npm-publish
+  queue: max
+  cancel-in-progress: false
+
 jobs:
   publish:
     runs-on: ubuntu-latest