testing: fix filter button position

Updated right margin of test filter

Author: connor4312

src/vs/workbench/contrib/testing/browser/media/testing.css

@@ -248,7 +248,7 @@
 	position: absolute;
 	top: 0;
 	bottom: 0;
-	right: 0;
+	right: 3px;
 	display: flex;
 	align-items: center;
 }