remove pypy support

Author: blink1073

.github/workflows/main.yml

@@ -69,7 +69,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: [3.6, 3.7, 3.8, 3.9, "3.10", "pypy-3.7"]
+        python-version: [3.6, 3.7, 3.8, 3.9, "3.10"]
 
     env:
       OS: ${{ matrix.os }}
@@ -90,13 +90,8 @@ jobs:
         run: mypy jupyter_client --exclude '\/tests|kernelspecapp|ioloop|runapp' --install-types --non-interactive
 
       - name: Run the tests with coverage
-        if: ${{ !startsWith(matrix.python-version, 'pypy') }}
         run: pytest --cov jupyter_client -v jupyter_client
 
-      - name: Run the tests on pypy
-        if: startsWith(matrix.python-version, 'pypy')
-        run: pytest -v jupyter_client
-
       - name: Build the docs
         run: |
           pip install -r requirements-doc.txt