probe: one runner, so that the answers arrive

Author: mcpplibs

.github/workflows/probe.yml

@@ -23,8 +23,11 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          # One runner. The answers this probe seeks --- which names libSystem
+          # exports, whether an entry point of one's own is accepted, whether the
+          # suspension primitive behaves --- are properties of the system rather
+          # than of the processor, and the x86_64 runner queues for half an hour.
           - { os: macos-14, arch: arm64 }
-          - { os: macos-13, arch: x86_64 }
     runs-on: ${{ matrix.os }}
     timeout-minutes: 20
     steps: