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>

pkg/runner/testdata/actions/docker-url/action.yml

@@ -8,9 +8,8 @@ inputs:
     default: World
 runs:
   using: docker
-  #image: docker://alpine:3.13
-  image: docker://node:12-alpine
+  image: docker://node:12-buster-slim
   env:
     TEST: enabled
-  args: 
-  - env
+  args:
+    - env