Fix string/regexp backslash escapes

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index b3308cb..45854f1 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -162,7 +162,7 @@
 list(SORT test_suites)
 foreach(test_suite ${test_suites})
     get_filename_component(data_name ${test_suite} NAME)
-    string(REGEX REPLACE "\.data$" "" data_name "${data_name}")
+    string(REGEX REPLACE "\\.data\$" "" data_name "${data_name}")
     string(REPLACE "test_suite_" "" data_name "${data_name}")
     string(REGEX MATCH "[^.]*" function_name "${data_name}")
     add_test_suite(${function_name} ${data_name})