Switch to xcode 11 which apparently works with coreclr debugging

https://github.com/dotnet/runtime/issues/42311#issuecomment-700718025

.github/workflows/build.yaml

@@ -116,6 +116,11 @@ jobs:
       with:
         dotnet-version: 3.1
 
+    - uses: maxim-lobanov/setup-xcode@v1
+      with:
+        xcode-version: ^11
+      name: "Switch to xcode 11 because of .NET debugging bug"
+
     - run: vim --version
       name: 'Print vim version information'
 
@@ -148,7 +153,7 @@ jobs:
     #   if: failure()
     #   with:
     #     NGROK_AUTH_TOKEN: ${{ secrets.NGROK_AUTH_TOKEN }}
-    #     SSH_PASS: ${{ secrets.SSH_PASS }}
+    #     SSH_PASS: ${{ secrets.SSH_PASS }} # [V]imspector
 
   PublishRelease:
     runs-on: 'ubuntu-16.04'