COMPMID-1743: Removed tabs from compare_keypoints' output

The tab characters were corrupting the output JSON file of arm_compute_validation

Change-Id: I8792fd0e02393aef60341552b428111e969a3927
diff --git a/tests/validation/Validation.h b/tests/validation/Validation.h
index 1f51fe9..1c4b2d4 100644
--- a/tests/validation/Validation.h
+++ b/tests/validation/Validation.h
@@ -688,7 +688,7 @@
 
     if(check_mismatches)
     {
-        ARM_COMPUTE_TEST_INFO("Checking for mismatches: ref count = " << std::distance(first1, last1) << " \ttarget count = " << std::distance(first2, last2));
+        ARM_COMPUTE_TEST_INFO("Checking for mismatches: ref count = " << std::distance(first1, last1) << " target count = " << std::distance(first2, last2));
     }
 
     int64_t num_missing    = 0;