Skip pypy3

Author: nicoddemus

.github/workflows/main.yml

@@ -86,6 +86,7 @@ jobs:
             python: "3.7"
             os: ubuntu-latest
             tox_env: "py37-freeze"
+            # coverage does not apply for freeze test, skip it
             skip_coverage: true
           - name: "ubuntu-py38"
             python: "3.8"
@@ -95,6 +96,8 @@ jobs:
             python: "pypy3"
             os: ubuntu-latest
             tox_env: "pypy3-xdist"
+            # coverage too slow with pypy3, skip it
+            skip_coverage: true
 
           - name: "macos-py37"
             python: "3.7"