Remove optional from json-simple managed dependency

Update `spring-boot-dependencies` so that `json-simple` does not include
an `<option>true</optional>` element.

Fixes gh-6450

Author: philwebb

spring-boot-dependencies/pom.xml

@@ -620,7 +620,6 @@
 				<groupId>com.googlecode.json-simple</groupId>
 				<artifactId>json-simple</artifactId>
 				<version>${simple-json.version}</version>
-				<optional>true</optional>
 			</dependency>
 			<dependency>
 				<groupId>com.h2database</groupId>