fix(gradle): jarFileTest caching

This was simply a call to project.file which has no effect on this task.
The inputs prefix was not added when this was added with commit:
b5331f4

Author: patrick-dedication

core/build.gradle

@@ -33,7 +33,7 @@ task jarFileTest(type: Test) {
     testClassesDirs = sourceSets.jarFileTest.output.classesDirs
     classpath = sourceSets.jarFileTest.runtimeClasspath
 
-    file(shadowJar.outputs.files.singleFile) // input for correct caching
+    inputs.file(shadowJar.outputs.files.singleFile) // input for correct caching
     systemProperty("jarFile", shadowJar.outputs.files.singleFile)
 
     dependsOn(shadowJar)