Use FetchContent_Populate

Reason: With it the source can be included directly and it does not install the header files

Author: Murmele

CMakeLists.txt

@@ -32,7 +32,9 @@ if (NOT ${FastFloat_FOUND})
       GIT_REPOSITORY https://github.com/fastfloat/fast_float.git
       GIT_TAG 1ea4f27b2aeee2859a1354a3c24cff52a116cad1
     )
-    FetchContent_MakeAvailable(FastFloat)
+    # FetchContent_MakeAvailable(FastFloat)
+    FetchContent_Populate(FastFloat)
+    add_subdirectory(${fastfloat_SOURCE_DIR} ${fastfloat_BINARY_DIR} EXCLUDE_FROM_ALL)
 endif()
 
 set(GCC_COMPILE_FLAGS "-Wextra -Wall -Wfloat-equal -Wundef -Wshadow \