Update images, fix extrapath (#723)

* fix: typo

* fix: remove debug for git references

it generates a massive amount of logs

* feat: read values from env

allows to test act on GHA when it's not a main repo

* fix: merge extrapath with PATH

* fix(tests): add additional shells for testing

* fix(image): update images

pin node to major version only, current node version: 12.22.1
replace most images with `node:12-buster-slim` to prevent
errors on macOS runner due to DockerHub pull limit
replace ocaml image

Co-authored-by: Casey Lee <cplee@nektos.com>

act/runner/testdata/commands/push.yml

@@ -14,8 +14,8 @@ jobs:
         id: set_output
         run: echo "::set-output name=zoo::zar"
 
-      #- run: echo "::add-path::/zip"
-      #- run: echo $PATH | grep /zip
+      - run: echo "::add-path::/zip"
+      - run: echo $PATH | grep /zip
 
       - name: TEST conditional
         if: steps.set_output.outputs.zoo