Feature add keep 730 (#740)

* Implemented #730, --keep

* Implemented #739, fixed --keep to accept relative paths

* Updated to macos-latest

Ref: https://github.com/actions/virtual-environments/issues/5583

* Release files for #730

.github/workflows/tests.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        os: [macos-10.15]
+        os: [macos-latest]
         python-version: ['3.8', '3.9', '3.10']
 
     steps: