build: skip setup-python on self-hosted runner

.github/workflows/insider-macos.yml

@@ -59,6 +59,7 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: '3.11'
+        if: env.VSCODE_ARCH == 'x64'
 
       - name: Clone VSCode repo
         env:

.github/workflows/stable-macos.yml

@@ -56,6 +56,7 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: '3.11'
+        if: env.VSCODE_ARCH == 'x64'
 
       - name: Clone VSCode repo
         run: . get_repo.sh