Fix a small CMake error

Author: jaja360

benchmarks/CMakeLists.txt

@@ -21,7 +21,7 @@ check_source_compiles(CXX "
 int main(void) {
     float valuef = 0;
     double valued = 0;
-    const char* ptr;
+    char* ptr;
     std::to_chars_result result1 = std::to_chars(ptr, ptr, valuef);
     std::to_chars_result result2 = std::to_chars(ptr, ptr, valued);
     return 0;

benchmarks/benchmark.cpp

@@ -22,9 +22,6 @@
 #include <string>
 #include <variant>
 #include <fast_float/fast_float.h>
-#if FROM_CHARS_SUPPORTED || TO_CHARS_SUPPORTED
-#include <charconv> // technically included by "algorithms.h"
-#endif
 
 using Benchmarks::arithmetic_float;
 using Benchmarks::BenchArgs;