lint-and-test: Expand pypy3 coverage from '3' to 3.6, 3.7 & 3.8.

Author: neiljp

.github/workflows/lint-and-test.yml

@@ -67,7 +67,9 @@ jobs:
           - {PYTHON: 3.8, OS: ubuntu-latest, NAME: "CPython 3.8 (ubuntu)"}
           - {PYTHON: 3.9, OS: ubuntu-latest, NAME: "CPython 3.9 (ubuntu)", CODECOV: true}
           - {PYTHON: "3.10", OS: ubuntu-latest, NAME: "CPython 3.10 (ubuntu)"}
-          - {PYTHON: 'pypy3', OS: ubuntu-latest, NAME: "PyPy 3 (ubuntu)"}
+          - {PYTHON: 'pypy-3.6', OS: ubuntu-latest, NAME: "PyPy 3.6 (ubuntu)"}
+          - {PYTHON: 'pypy-3.7', OS: ubuntu-latest, NAME: "PyPy 3.7 (ubuntu)"}
+          - {PYTHON: 'pypy-3.8', OS: ubuntu-latest, NAME: "PyPy 3.8 (ubuntu)"}
           - {PYTHON: 3.9, OS: macos-latest, NAME: "CPython 3.9 (macos)"}
     runs-on: ${{ matrix.env.OS }}
     name: Install & test - ${{ matrix.env.NAME}}
@@ -81,8 +83,8 @@ jobs:
         run: python --version
       - name: Upgrade pip
         run: python -m pip install --upgrade pip
-      - name: Ensure libxml-related libraries are installed (pypy3 only)
-        if: matrix.env.PYTHON == 'pypy3'
+      - name: Ensure libxml-related libraries are installed (pypy-3.6 only)
+        if: matrix.env.PYTHON == 'pypy-3.6'
         run: sudo apt install libxml2-dev libxslt1-dev
       - name: Ensure regular package installs from checkout
         run: pip install .