Upgrade to SolrJ 5.5.1

Closes gh-5958

spring-boot-dependencies/pom.xml

@@ -139,7 +139,7 @@
 		<simple-json.version>1.1.1</simple-json.version>
 		<slf4j.version>1.7.21</slf4j.version>
 		<snakeyaml.version>1.17</snakeyaml.version>
-		<solr.version>5.5.0</solr.version>
+		<solr.version>5.5.1</solr.version>
 		<spock.version>1.0-groovy-2.4</spock.version>
 		<spring.version>4.3.0.RC2</spring.version>
 		<spring-amqp.version>1.6.0.RC1</spring-amqp.version>