[java-truffle] don't exclude graal-sdk dependency

I added the exclusion as a hack to work around classpath
issues after importing the project into Eclipse, but this
isn't the right thing to do.

It prevents compilation on JDKs other than Graal, which was
not my intent.

impls/java-truffle/build.gradle

@@ -14,9 +14,7 @@ repositories {
 }
 
 dependencies {
-    implementation('org.graalvm.truffle:truffle-api:21.1.0') {
-      exclude group: 'org.graalvm.sdk', module: 'graal-sdk'
-    }
+    implementation 'org.graalvm.truffle:truffle-api:21.1.0'
     implementation 'org.organicdesign:Paguro:3.2.0'
     annotationProcessor 'org.graalvm.truffle:truffle-dsl-processor:21.1.0'
 }