tests/paste: Add test to avoid trimming extra whitespace

tests/by-util/test_paste.rs

@@ -72,6 +72,12 @@ static EXAMPLE_DATA: &[TestData] = &[
         ins: &["1\na\n", "2\nb\n"],
         out: "1💣a\n2💣b\n",
     },
+    TestData {
+        name: "trailing whitespace",
+        args: &["-d", "|"],
+        ins: &["1 \na \n", "2\t\nb\t\n"],
+        out: "1 |2\t\na |b\t\n",
+    },
 ];
 
 #[test]