clang-tidy: Enable readability-redundant-string-cstr check

This check finds unnecessary calls to std::string::c_str() and
std::string::data().

Change-Id: I43e747b95eb042650668da7dd57a8d4b8463426a
Signed-off-by: Pavithra Barithaya <pavithrabarithaya07@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
index fed8f0d..462941c 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -261,6 +261,7 @@
 readability-redundant-member-init,
 readability-redundant-preprocessor,
 readability-redundant-smartptr-get,
+readability-redundant-string-cstr,
 readability-redundant-string-init,
 readability-simplify-boolean-expr,
 readability-simplify-subscript-expr,