Added missing #include <tuple> in tz.cpp

This is needed for std::tie. GCC and Clang are fine with it missing, but
my Visual Studio doesn't like it.

tz.cpp

@@ -87,6 +87,7 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <tuple>
 #include <vector>
 #include <sys/stat.h>