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/basic/push.yml

@@ -10,12 +10,12 @@ jobs:
     steps:
       - run: echo ${{ env.TEST }} | grep value
       - run: env
-      - uses: docker://alpine:3.13
+      - uses: docker://node:12-buster-slim
         with:
           somekey: ${{ env.TEST }}
           args: echo ${INPUT_SOMEKEY} | grep somevalue
       - run: ls
-      - run: echo 'hello world' 
+      - run: echo 'hello world'
       - run: echo ${GITHUB_SHA} >> $(dirname "${GITHUB_WORKSPACE}")/sha.txt
       - run: cat $(dirname "${GITHUB_WORKSPACE}")/sha.txt | grep ${GITHUB_SHA}
   build:
@@ -29,10 +29,10 @@ jobs:
     runs-on: ubuntu-latest
     needs: [build]
     steps:
-      - uses: docker://ubuntu:18.04
+      - uses: docker://node:12-buster-slim
         with:
           args: env
-      - uses: docker://ubuntu:18.04
+      - uses: docker://node:12-buster-slim
         with:
           entrypoint: /bin/echo
           args: ${{github.event_name}}