Fix compilation with xcode 16.3 (#205)

xcode 16.3 ships with clang17 as default compiler.
This version of clang warns about casts between incompatible function types,
and v8 has some of those:
```
include/node/v8-persistent-handle.h:512:26: error: cast from 'typename WeakCallbackInfo<ObjectWrap>::Callback' (aka 'void (*)(const WeakCallbackInfo<ObjectWrap> &)') to 'Callback' (aka 'void (*)(const WeakCallbackInfo<void> &)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
```

This commit adds a -Wno-cast-function-type-mismatch flag to the compiler
flags to suppress these warnings (that would otherwise cause errors because
of the -Werror flag) and also a -Wno-unknown-warning-option flag to suppress
the warning about the unknown warning option "-Wcast-function-type-mismatch"
for clang < 17.

Author: nsavoire

binding.gyp

@@ -83,6 +83,8 @@
                 'xcode_settings': {
                     'OTHER_CFLAGS+': [
                         "-Wno-deprecated-declarations",
+                        "-Wno-cast-function-type-mismatch", # clang17 now warns about casts between incompatible function types and v8 has some of those
+                        "-Wno-unknown-warning-option", # "-Wcast-function-type-mismatch" is not a valid warning option for clang < 17
                         "-Werror",
                         '-std=gnu++20',
                         ],