Drop pypy 2.7 testing environment

Unfortunately it is breaking hard and I don't have time available to
investigate this now.

Author: nicoddemus

.github/workflows/main.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["2.7", "3.5", "3.6", "3.7", "3.8", "3.9", "pypy-3.7", "pypy-2.7"]
+        python: ["2.7", "3.5", "3.6", "3.7", "3.8", "3.9", "pypy-3.7"]
         os: [ubuntu-latest, windows-latest]
         include:
           - python: "2.7"
@@ -25,8 +25,6 @@ jobs:
             tox_env: "py38"
           - python: "3.9"
             tox_env: "py39"
-          - python: "pypy-2.7"
-            tox_env: "pypy2"
           - python: "pypy-3.7"
             tox_env: "pypy3"