Replace deprecated macos CI runners

Replace macos-11 runners with macos-14 runners.

Reference: https://github.com/actions/runner-images?tab=readme-ov-file#available-images
Signed-off-by: Ayan Sinha Mahapatra <ayansmahapatra@gmail.com>

azure-pipelines.yml

@@ -23,14 +23,6 @@ jobs:
           test_suites:
               all: venv/bin/pytest -n 2 -vvs
 
-    - template: etc/ci/azure-posix.yml
-      parameters:
-          job_name: macos11_cpython
-          image_name: macOS-11
-          python_versions: ['3.8', '3.9', '3.10', '3.11', '3.12']
-          test_suites:
-              all: venv/bin/pytest -n 2 -vvs
-
     - template: etc/ci/azure-posix.yml
       parameters:
           job_name: macos12_cpython
@@ -55,6 +47,14 @@ jobs:
           test_suites:
               all: venv/bin/pytest -n 2 -vvs
 
+    - template: etc/ci/azure-posix.yml
+      parameters:
+          job_name: macos11_cpython
+          image_name: macOS-14-large
+          python_versions: ['3.7', '3.8', '3.9', '3.10', '3.11']
+          test_suites:
+              all: venv/bin/pytest -n 2 -vvs
+
     - template: etc/ci/azure-win.yml
       parameters:
           job_name: win2019_cpython