Add boost-rational to vcpkg.json

vcpkg update has bumped boost from 1.83.0 to 1.84.0 and now boost-rational doesn't get pulled in automatically. Presumably it used to come through boost-math.

Author: firthm01

vcpkg.json

@@ -23,6 +23,7 @@
     "boost-program-options",
     "boost-property-tree",
     "boost-range",
+    "boost-rational",
     "boost-smart-ptr",
     "boost-test",
     "boost-timer",