fatal error: 'vector' file not found on macos after upgrading

[kylebaron]

A couple of reports of errors like this after upgrading OS on mac. The solution was to update Xcode.

> library(mrgsolve)
> mod <- modlib("pk1")
Building pk1 ... error.

---:: stderr ::---------------------------------------------
using C++ compiler: ‘Apple clang version 16.0.0 (clang-1600.0.26.4)’
using SDK: ‘MacOSX15.1.sdk’
In file included from pk1-mread-source.cpp:3:
In file included from ./pk1-mread-header.h:11:
/Users/i0568108/Library/R/arm64/4.3/library/mrgsolve/base/mrgsolv.h:25:10: fatal error: 'vector' file not found
   25 | #include <vector>
      |          ^~~~~~~~
1 error generated.
make: *** [pk1-mread-source.o] Error 1
------------------------------------------------------------
Error: the model build step failed.
------------------------------------------------------------
Error: the model build step failed.