Switch from tox to nox to align with PyO3 and thereby hopefully get a working CI on Windows Server 2022.

Author: adamreichold

.github/workflows/ci.yml

@@ -35,8 +35,8 @@ jobs:
         platform: [
           { os: "ubuntu-latest", python-architecture: "x64", rust-target: "x86_64-unknown-linux-gnu" },
           { os: "macOS-latest",   python-architecture: "x64", rust-target: "x86_64-apple-darwin" },
-          { os: "windows-2019", python-architecture: "x64", rust-target: "x86_64-pc-windows-msvc" },
-          { os: "windows-2019", python-architecture: "x86", rust-target: "i686-pc-windows-msvc" },
+          { os: "windows-latest", python-architecture: "x64", rust-target: "x86_64-pc-windows-msvc" },
+          { os: "windows-latest", python-architecture: "x86", rust-target: "i686-pc-windows-msvc" },
         ]
         include:
           # NumPy does not provide pre-built wheels for PyPy on macOS and Windows
@@ -76,13 +76,12 @@ jobs:
         if: ${{ !startsWith(matrix.python-version, 'pypy') }}
       - name: Test example
         run: |
-          pip install tox
-          tox -c examples/simple-extension
+          pip install nox
+          nox -f examples/simple-extension/noxfile.py
     env:
       CARGO_TERM_VERBOSE: true
       CARGO_BUILD_TARGET: ${{ matrix.platform.rust-target }}
       RUST_BACKTRACE: 1
-      TOX_TESTENV_PASSENV: CARGO_BUILD_TARGET
 
   check-msrv:
     runs-on: ubuntu-latest
@@ -131,9 +130,8 @@ jobs:
         shell: python
       - name: Test example
         run: |
-          pip install tox
-          tox
-        working-directory: examples/simple-extension
+          pip install nox
+          nox -f examples/simple-extension/noxfile.py
 
   examples:
     runs-on: ubuntu-latest
@@ -155,9 +153,9 @@ jobs:
         continue-on-error: true
       - name: Test examples
         run: |
-          pip install tox
-          tox -c examples/linalg
-          tox -c examples/parallel
+          pip install nox
+          nox -f examples/linalg/noxfile.py
+          nox -f examples/parallel/noxfile.py
 
   coverage:
     runs-on: ubuntu-latest

examples/linalg/noxfile.py

@@ -0,0 +1,8 @@
+import nox
+
+
+@nox.session
+def tests(session):
+    session.install('pip', 'numpy', 'pytest')
+    session.run('pip', 'install', '.', '-v')
+    session.run('pytest')

examples/linalg/tox.ini

@@ -0,0 +1,8 @@
+import nox
+
+
+@nox.session
+def tests(session):
+    session.install('pip', 'numpy', 'pytest')
+    session.run('pip', 'install', '.', '-v')
+    session.run('pytest')

examples/parallel/noxfile.py

@@ -0,0 +1,8 @@
+import nox
+
+
+@nox.session
+def tests(session):
+    session.install('pip', 'numpy', 'pytest')
+    session.run('pip', 'install', '.', '-v')
+    session.run('pytest')