OpenGrok-2366 upgrade to latest lucene 7.5.0, closes #2366

Author: Lubos Kosco

pom.xml

@@ -60,7 +60,7 @@ Portions Copyright (c) 2018, Chris Fraire <[email protected]>.
     </scm>
 
     <properties>
-        <lucene.version>7.4.0</lucene.version>
+        <lucene.version>7.5.0</lucene.version>
         <mavenjavadocplugin.version>2.10.4</mavenjavadocplugin.version>
         <compileSource>1.8</compileSource>
         <compileTarget>1.8</compileTarget>