Upgrade to SOLR 9

Author: bserem

docker-compose.solr.yaml

@@ -31,7 +31,7 @@ services:
     # and code at https://github.com/docker-solr/docker-solr
     # README: https://github.com/docker-solr/docker-solr/blob/master/README.md
     # It's almost impossible to work with it if you don't read the docs there
-    image: solr:8
+    image: solr:9
     restart: "no"
     # Solr is served from this port inside the container.
     expose: