Merge pull request #125 from iterative/reduce-max-parallel

gh: reduce the max-parallel to 3

Author: efiop

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       fail-fast: false
-      max-parallel: 4
+      max-parallel: 3
       matrix:
         os: [ubuntu-18.04, macos-10.15, windows-2019]
         pyv: ["3.6", "3.7", "3.8", "3.9"]