fix: remove include <ranges> (XRPLF#4788)

Remove dependency on `<ranges>` header, since it is not implemented by
all compilers which we want to support.

This code change only affects unit tests.

Resolve XRPLF#4787

src/test/jtx/TestHelpers.h

@@ -27,17 +27,25 @@
 #include <ripple/protocol/jss.h>
 #include <test/jtx/Env.h>
 
-#include <ranges>
+#include <vector>
 
 namespace ripple {
 namespace test {
 namespace jtx {
 
-// Helper to make vector from iterable
+// TODO We only need this long "requires" clause as polyfill, for C++20
+// implementations which are missing <ranges> header. Replace with
+// `std::ranges::range<Input>`, and accordingly use std::ranges::begin/end
+// when we have moved to better compilers.
+template <typename Input>
 auto
-make_vector(auto const& input) requires std::ranges::range<decltype(input)>
+make_vector(Input const& input) requires requires(Input& v)
 {
-    return std::vector(std::ranges::begin(input), std::ranges::end(input));
+    std::begin(v);
+    std::end(v);
+}
+{
+    return std::vector(std::begin(input), std::end(input));
 }
 
 // Functions used in debugging