CI: dogfooding should run on the same Mac runner as validate (#10101)

Author: ulysses4ever

Diff for: .github/workflows/validate.yml

@@ -343,7 +343,7 @@ jobs:
     needs: validate
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-13, windows-latest]
         # We only use one ghc version the used one for the next release (defined at top of the workflow)
         # We need to build an array dynamically to inject the appropiate env var in a previous job,
         # see https://docs.github.com/en/actions/learn-github-actions/expressions#fromjson