CentOS 7: installed devtoolset-7, but GCC 7.8 is using GCC 4.8 installation’s old C++ include files

I'm trying to compile and install Pistache on a CentOS 7 machine, following their instructions.

This is a package that requires C++ 11, so since the Development Tools package on CentOS 7 installs an old version of gcc (4.8.3) that doesn't support C++ 11 features, I've installed devtoolset-7 and enabled it with scl enable devtoolset-7 bash. This appears to be functioning properly, as gcc --version displays gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5).

However, when I try to make the Pistache sources, I get this compilation error:

/root/compiler_installation_script/pistache/src/server/router.cc:102:45: error: no matching function for call to ‘regex_replace(const string&, std::regex&, const char [2])’
     SegmentTreeNode::multiple_slash, "/");
                                         ^
 /root/compiler_installation_script/pistache/src/server/router.cc:102:45: note: candidates are:
 In file included from /usr/include/c++/4.8.2/regex:62:0,

Unless I'm misunderstanding, this seems to indicate that my compiler is using outdated C++ include headers that are compatible with gcc 4.8.3, resulting in the error. How can I fix this?

Note: I'm sure the issue isn't with Pistache source itself, as I've compiled this successfully on other machines, including a fresh CentOS 7 machine yesterday.