Upgrade Apache HTTP components to 4.4.5

Closes gh-6165

Author: snicoll

spring-boot-dependencies/pom.xml

@@ -84,7 +84,7 @@
 		<hsqldb.version>2.3.4</hsqldb.version>
 		<httpasyncclient.version>4.1.1</httpasyncclient.version>
 		<httpclient.version>4.5.2</httpclient.version>
-		<httpcore.version>4.4.4</httpcore.version>
+		<httpcore.version>4.4.5</httpcore.version>
 		<infinispan.version>8.0.2.Final</infinispan.version>
 		<jackson.version>2.6.6</jackson.version>
 		<janino.version>2.7.8</janino.version>