Fix signed/unsigned comparision

psrdada_cpp/effelsberg/edd/test/src/GatedSpectrometerTest.cu

@@ -585,7 +585,7 @@ TEST_P(ExecutionTests, SinglePolOutput)
     // 3 Block, set value and SCI
     raw_buffer[122] =  int8_t(13);
     uint64_t* sc_items = reinterpret_cast<uint64_t*>(raw_buffer + params.nHeaps * heapSize);
-    for (int i = 0; i < params.nHeaps; i++)
+    for (size_t i = 0; i < params.nHeaps; i++)
         SET_BIT(sc_items[i], 0);
     EXPECT_NO_THROW(spectrometer(buff)) << params.msg;