Go back to nose for Appveyor

pytest & Appveyor appear to give erroneous
coverage info, so revert for now.
This reverts commit 5f9df28.

.appveyor.yml

@@ -4,19 +4,19 @@ environment:
   matrix:
     - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015, PYTHON: "C:\\Python27"}
     - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019, PYTHON: "C:\\Python37-x64"}
+    - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019, PYTHON: "C:\\Python38"}
     - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019, PYTHON: "C:\\Python38-x64"}
     - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019, PYTHON: "C:\\Python39-x64"}
-    - {APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022, PYTHON: "C:\\Python313-x64"}
 
 install:
   - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
-  - "python.exe -m pip install codecov coverage pytest-cov setuptools"
+  - "python.exe -m pip install codecov coverage nose"
   - "python.exe -m pip install -r requirements.txt"
 
 build: off
 
 test_script:
-  - "py.test --cov=ihm --cov-branch -v ."
+  - "nosetests --with-coverage --cover-branches"
 
 on_success:
   - "codecov"