Increase max heap size

core/sail/memory/src/test/java/org/eclipse/rdf4j/sail/memory/benchmark/MemValueFactoryConcurrentBenchmark.java

@@ -58,7 +58,7 @@
 @State(Scope.Benchmark)
 @Warmup(iterations = 5)
 @BenchmarkMode({ Mode.AverageTime })
-@Fork(value = 1, jvmArgs = { "-Xms20G", "-Xmx20G", })
+@Fork(value = 1, jvmArgs = { "-Xms1G", "-Xmx50G", })
 @Measurement(iterations = 5)
 @OutputTimeUnit(TimeUnit.MILLISECONDS)
 public class MemValueFactoryConcurrentBenchmark extends BaseConcurrentBenchmark {