pom.xml: update comment about org.checkerframework:checker-qual

Both com.google.guava:guava and org.apache.solr:solr-core depend on
org.checkerframework:checker-qual, but org.postgresql:postgresql no
longer does.

Author: alanorth

pom.xml

@@ -1860,7 +1860,7 @@
                 <artifactId>guava</artifactId>
                 <version>32.1.3-jre</version>
                 <exclusions>
-                    <!-- Use version provided by Solr / Postgres -->
+                    <!-- Use version provided by solr-core -->
                     <exclusion>
                         <groupId>org.checkerframework</groupId>
                         <artifactId>checker-qual</artifactId>