Update to com.squareup.okhttp3 3.12.8

Fixes gh-7915

gradle/dependency-management.gradle

@@ -18,7 +18,7 @@ dependencyManagement {
 	}
 	dependencies {
 		dependency 'cglib:cglib-nodep:3.2.12'
-		dependency 'com.squareup.okhttp3:mockwebserver:3.12.3'
+		dependency 'com.squareup.okhttp3:mockwebserver:3.12.8'
 		dependency 'opensymphony:sitemesh:2.4.2'
 		dependency 'org.gebish:geb-spock:0.10.0'
 		dependency 'org.jasig.cas:cas-server-webapp:4.2.7'
@@ -56,7 +56,7 @@ dependencyManagement {
 		dependency 'com.nimbusds:lang-tag:1.4.3'
 		dependency 'com.nimbusds:nimbus-jose-jwt:6.0.2'
 		dependency 'com.nimbusds:oauth2-oidc-sdk:6.0'
-		dependency 'com.squareup.okhttp3:okhttp:3.12.2'
+		dependency 'com.squareup.okhttp3:okhttp:3.12.8'
 		dependency 'com.squareup.okio:okio:1.13.0'
 		dependency 'com.sun.xml.bind:jaxb-core:2.3.0.1'
 		dependency 'com.sun.xml.bind:jaxb-impl:2.3.2'