Swap cogniteenv/echo for alpine:3.10.1

testing/resources/docker_hooks_repo/Dockerfile

@@ -1,3 +1,3 @@
-FROM cogniteev/echo
+FROM alpine:3.10.1
 
 CMD ["echo", "This is overwritten by the .pre-commit-hooks.yaml 'entry'"]

testing/resources/docker_image_hooks_repo/.pre-commit-hooks.yaml

@@ -1,8 +1,8 @@
 -   id: echo-entrypoint
     name: echo (via --entrypoint)
     language: docker_image
-    entry: --entrypoint echo cogniteev/echo
+    entry: --entrypoint echo alpine:3.10.1
 -   id: echo-cmd
     name: echo (via cmd)
     language: docker_image
-    entry: cogniteev/echo echo
+    entry: alpine:3.10.1 echo