actions: downgrade macos runners to macos 11 (#5892)

Author: oliver-sanders

.github/workflows/test_fast.yml

@@ -22,7 +22,7 @@ jobs:
         os: ['ubuntu-latest']
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
         include:
-          - os: 'macos-latest'
+          - os: 'macos-11'
             python-version: '3.7'
     env:
       PYTEST_ADDOPTS: --cov --cov-append -n 5 --color=yes

.github/workflows/test_functional.yml

@@ -74,13 +74,13 @@ jobs:
             platform: '_remote_background_indep_tcp _remote_at_indep_tcp'
           # macos
           - name: 'macos 1/5'
-            os: 'macos-latest'
+            os: 'macos-11'
             python-version: '3.7'
             test-base: 'tests/f'
             chunk: '1/5'
             platform: '_local_background*'
           - name: 'macos 2/5'
-            os: 'macos-latest'
+            os: 'macos-11'
             python-version: '3.7'
             test-base: 'tests/f'
             chunk: '2/5'