fix: use correct c++ version on OSX for Node.js 20+ (#32)

For some reason this is not an issue on Linux, so as to avoid a breaking
change, only use C++17 on OS X if the Node.js version is at least v20.

.github/workflows/pr.yml

@@ -4,9 +4,10 @@ on: [pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: [ubuntu-latest, macos-latest]
         node-version: [16, 18, 20]
     steps:
       - uses: actions/checkout@v2

.github/workflows/snapshot.yml

@@ -8,9 +8,10 @@ on:
 jobs:
   build:
     if: ${{ github.repository == 'Netflix-Skunkworks/spectator-js-nodejsmetrics' }}
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: [ubuntu-latest, macos-latest]
         node-version: [16, 18, 20]
     steps:
       - uses: actions/checkout@v2

binding.gyp

@@ -1,4 +1,12 @@
 {
+  'variables': {
+    'osx_cpp_version': "14",
+    'conditions': [
+        [ 'OS=="mac" and node_module_version >= 115', {
+            'osx_cpp_version': "17"
+        }]
+    ]
+  },
   'targets': [
     {
       'target_name': 'spectator_internals',
@@ -10,7 +18,7 @@
       'conditions': [
         [ 'OS=="mac"', {
           'xcode_settings': {
-            'OTHER_CPLUSPLUSFLAGS' : ['-stdlib=libc++', '-v', '-std=c++14', '-Wall', '-Wextra', '-Wno-unused-parameter', '-g', '-O2' ],
+            'OTHER_CPLUSPLUSFLAGS' : ['-stdlib=libc++', '-v', '-std=c++<(osx_cpp_version)', '-Wall', '-Wextra', '-Wno-unused-parameter', '-g', '-O2' ],
             'OTHER_LDFLAGS': ['-stdlib=libc++'],
             'MACOSX_DEPLOYMENT_TARGET': '10.12',
             'GCC_ENABLE_CPP_EXCEPTIONS': 'NO'