Trying to fix CI issues

Mac builds spewed a ton of output related to math.h but the very first
output was:

In file included from /Users/runner/work/prima/prima/c/prima.c:6:
    /usr/local/Cellar/gcc@13/13.3.0/lib/gcc/13/gcc/x86_64-apple-darwin21/13/include-fixed/math.h:568:68: error: macro "__API_DEPRECATED_MSG3" requires 3 arguments, but only 2 given
      568 | __API_DEPRECATED("use `(float)INFINITY` instead", macos(10.0, 10.9)) __API_UNAVAILABLE(ios, watchos, tvos);

It looks like an error with math.h as opposed to our use of INFINITY,
but I'm going to try listening to the message and hopefully that fixes
the mac build.

c/prima.c

@@ -56,7 +56,7 @@ prima_rc_t prima_init_options(prima_options_t *const options)
     options->rhobeg = NAN;  // Will be interpreted by Fortran as not present
     options->rhoend = NAN;  // Will be interpreted by Fortran as not present
     options->iprint = PRIMA_MSG_NONE;
-    options->ftarget = -INFINITY;
+    options->ftarget = -(float)INFINITY;
     options->ctol = sqrt(DBL_EPSILON);
     return PRIMA_RC_DFT;
 }