Fix to link to the 'processResources' task of the current source set

This was only working correctly when the 'sol' files are in the 'main'
source set. But not for files in 'test' or other custom source sets.

Follow up to the Configuration Cache fix.

Signed-off-by: Jendrik Johannes <jendrik.johannes@gmail.com>

Author: jjohannes

src/main/groovy/org/web3j/solidity/gradle/plugin/SolidityPlugin.groovy

@@ -148,7 +148,7 @@ class SolidityPlugin implements Plugin<Project> {
             })
         }
 
-        project.tasks.named('processResources', ProcessResources) {
+        project.tasks.named(sourceSet.processResourcesTaskName, ProcessResources) {
             it.from(compileTask)
         }
     }