Fix missing #include <algorithm> in zip.hpp

A couple of the zip functions use the init-list overload of std::min. Unfortunately this means we need to bring in the <algorithm> header (previously we happened to be getting away without it on all three platforms).

I'd rather avoid dragging in this large header, so a better long-term solution would be to add an overload of our own cmp::min which does the equivalent of std:min({ilist...})

include/flux/op/zip.hpp

@@ -9,6 +9,8 @@
 #include <flux/core.hpp>
 #include <flux/source/empty.hpp>
 
+#include <algorithm> // for std::min({ilist...})
+
 namespace flux {
 
 namespace detail {

module/flux.cpp

@@ -1,6 +1,7 @@
 
 module;
 
+#include <algorithm>
 #include <array>
 #include <bitset>
 #include <compare>