CI: push MacOS jobs to MacOS 13 and 14 (#3002)

Github has finally released those as free and retired macos-11

.github/workflows/macos_build.yml

@@ -15,7 +15,7 @@ jobs:
           - "3.10"
           - "3.11"
           - "3.12"
-    runs-on: macos-11
+    runs-on: macos-14
     steps:
       - uses: actions/checkout@v4
       # Normally, we would use the superbly maintained...

.github/workflows/modified_scripts_build.yml

@@ -30,7 +30,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ${{fromJson(needs.discover_modified_scripts.outputs.versions)}}
-        os: ["macos-11", "macos-12"]
+        os: ["macos-13", "macos-14"]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4

.github/workflows/pyenv_tests.yml

@@ -12,8 +12,8 @@ jobs:
         os:
           - ubuntu-22.04
           - ubuntu-20.04
-          - macos-12
-          - macos-11
+          - macos-14
+          - macos-13
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4