Fix intended backslash in test data

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/test_generate_test_code.py b/tests/scripts/test_generate_test_code.py
index f366753..ae1aa2a 100755
--- a/tests/scripts/test_generate_test_code.py
+++ b/tests/scripts/test_generate_test_code.py
@@ -746,8 +746,8 @@
         data = '''/* comment */
 /* more
  * comment */
-// this is\
-still \
+// this is\\
+still \\
 a comment
 void func()
 {