Modify regex for clang format

[boulderdaze]

Modified regex for clang format.

The current REGEX failed to list an external header with - above system headers. (The example is from tuvx, which I found the failure.)
Current:

#include <tuvx/util/config_yaml.h>

#include <cstring>
#include <fstream>

#include <yaml-cpp/yaml.h>

This PR:

#include <tuvx/util/config_yaml.h>

#include <yaml-cpp/yaml.h>

#include <cstring>
#include <fstream>