fix: missing <locale> header file added

src/core/include/mp-units/bits/core_gmf.h

@@ -35,6 +35,7 @@
 #include <initializer_list>
 #include <iterator>
 #include <limits>
+#include <locale>
 #include <numbers>
 #include <numeric>
 #include <optional>

src/core/include/mp-units/format.h

@@ -32,6 +32,10 @@
 #include <mp-units/framework/quantity.h>
 #include <mp-units/framework/unit.h>
 
+#ifndef MP_UNITS_IN_MODULE_INTERFACE
+#include <locale>
+#endif
+
 namespace mp_units::detail {
 
 template<typename Char>