plugin.py::get_python_version - new pypy support

actions/setup-python#136

Changes slightly how pypy version strings are handled to match more
recent github actions changes.

src/tox_gh_actions/plugin.py

@@ -108,12 +108,13 @@ def get_python_version():
     """Get Python version running in string (e.g,. 3.8)
 
     - CPython => 2.7, 3.8, ...
-    - PyPy => pypy2, pypy3
+    - PyPy => pypy-2.7, pypy-3.7
     """
-    if "PyPy" in sys.version:
-        return "pypy" + str(sys.version_info[0])
     # Assuming running on CPython
-    return ".".join([str(i) for i in sys.version_info[:2]])
+    version = ".".join([str(i) for i in sys.version_info[:2]])
+    if "PyPy" in sys.version:
+        version = "pypy-" + version
+    return version
 
 
 def is_running_on_actions():

tests/test_plugin.py

@@ -289,7 +289,7 @@ def test_get_envlist_from_factors(envlist, factors, expected):
             "3.6.9 (1608da62bfc7, Dec 23 2019, 10:50:04)\n"
             "[PyPy 7.3.0 with GCC 7.3.1 20180303 (Red Hat 7.3.1-5)]",
             (3, 6, 9, "final", 0),
-            "pypy3",
+            "pypy-3.6",
         ),
         (
             "2.7.13 (724f1a7d62e8, Dec 23 2019, 15:36:24)\n"