Revert "Remove potentially unnecessary shell"

This reverts commit c180dde.

modules/actions/exec.js

@@ -112,6 +112,10 @@ const exec = async (info) => {
           // spawnProcess defaults does not apply to dockerExec so we need to
           // provide these explicitly here.
           inheritStderr: true,
+          spawnOptions: {
+            ...opts.spawnOptions,
+            shell: true,
+          },
           ...opts,
         }
       )