CI: update workflow

.github/workflows/main.yml

@@ -22,15 +22,15 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
 
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install black 'isort[colors]<6'
+          pip install -v --editable .[lint]
 
       - name: black check
         run: |
@@ -40,6 +40,10 @@ jobs:
         run: |
           python -m isort --check --diff --color .
 
+      - name: cython-lint check
+        run: |
+          cython-lint src/pykrige/
+
   build_wheels:
     name: wheels for ${{ matrix.cfg.os }} / ${{ matrix.cfg.arch }}
     runs-on: ${{ matrix.cfg.os }}
@@ -61,7 +65,7 @@ jobs:
           fetch-depth: '0'
 
       - name: Build wheels
-        uses: pypa/cibuildwheel@v2.16.2
+        uses: pypa/cibuildwheel@v2.17.0
         env:
           CIBW_ARCHS: ${{ matrix.cfg.arch }}
         with:
@@ -74,18 +78,16 @@ jobs:
   build_sdist:
     name: sdist and coveralls
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
 
     steps:
       - uses: actions/checkout@v2
         with:
           fetch-depth: '0'
 
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
 
       - name: Install dependencies
         run: |