Upgrade to Jetty El 8.5.40

Closes gh-16776

Author: snicoll

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -106,7 +106,7 @@
 		<jest.version>6.3.1</jest.version>
 		<jetty.version>9.4.18.v20190429</jetty.version>
 		<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>
-		<jetty-el.version>8.5.35.1</jetty-el.version>
+		<jetty-el.version>8.5.40</jetty-el.version>
 		<jetty-reactive-httpclient.version>1.0.3</jetty-reactive-httpclient.version>
 		<jmustache.version>1.14</jmustache.version>
 		<jna.version>4.5.2</jna.version>