Switch to Tomcat's EL reference implementation

Closes gh-871

spring-restdocs-core/build.gradle

@@ -65,7 +65,7 @@ dependencies {
 	testImplementation("org.mockito:mockito-core")
 	testImplementation("org.springframework:spring-test")
 
-	testRuntimeOnly("org.glassfish:jakarta.el:4.0.2")
+	testRuntimeOnly("org.apache.tomcat.embed:tomcat-embed-el")
 }
 
 jar {

spring-restdocs-platform/build.gradle

@@ -14,6 +14,7 @@ dependencies {
 		api("junit:junit:4.13.1")
 		api("org.apache.pdfbox:pdfbox:2.0.27")
 		api("org.apache.tomcat.embed:tomcat-embed-core:10.1.1")
+		api("org.apache.tomcat.embed:tomcat-embed-el:10.1.1")
 		api("org.asciidoctor:asciidoctorj:2.5.6")
 		api("org.asciidoctor:asciidoctorj-pdf:2.3.0")
 		api("org.assertj:assertj-core:3.23.1")