chore(ci): Test on Python 3.14 release candidate 3

Python v3.14 -- October 7th
* https://www.python.org/download/pre-releases
* https://www.python.org/downloads/release/python-3140rc3

Also, upgrade from deprecated `macos-13` to `macos-15-intel`.

The currently available GitHub Actions macOS runners are:
| macOS Version | runner.arch |
|---------------|-------------|
| macos-13 | X64 |
| macos-14 | ARM64 |
| macos-15 | ARM64 |
| macos-15-intel | X64 |
| macos-26 | ARM64 |
| macos-latest | ARM64 |
* Let's prepare for actions/runner-images#13046

Author: cclauss

.github/workflows/node-gyp.yml

@@ -11,17 +11,17 @@ jobs:
       matrix:
         node-version: ["22"]
         os: [macos-latest, ubuntu-latest, windows-latest]
-        python-version: ["3.9", "3.11", "3.13"]
+        python-version: ["3.10", "3.12", "3.14"]
         include:
           - node-version: "22"
-            os: macos-13  # macOS on Intel
-            python-version: "3.13"
+            os: macos-15-intel  # macOS on Intel
+            python-version: "3.14"
           - node-version: "22"
             os: ubuntu-24.04-arm  # Ubuntu on ARM
-            python-version: "3.13"
+            python-version: "3.14"
           - node-version: "22"
             os: windows-11-arm  # Windows on ARM
-            python-version: "3.13"
+            python-version: "3.14"
     runs-on: ${{ matrix.os }}
     steps:
       - name: Clone gyp-next