Solr: remove reference to Shalin

Shalin isn't active in the Solr project anymore.

library/solr

@@ -1,7 +1,6 @@
 # this file is generated via https://github.com/apache/solr-docker/blob/e743474ec59206f53e6c1003cc852f104b315d43/generate-stackbrew-library.sh
 
 Maintainers: The Apache Solr Project <[email protected]> (@asfbot),
- Shalin Mangar (@shalinmangar),
  David Smiley (@dsmiley),
  Jan Høydahl (@janhoy),
  Houston Putman (@houstonputman)