actions: add test for hashFiles()

As of

7c7d80ebdd

a step with hashFiles('...') will lookup the file from the container
running the job.

actions/example-expression/.forgejo/workflows/test.yml

@@ -98,10 +98,11 @@ jobs:
           set -x
           test "${{ fromJSON('["one","two"]')[0] }}" = 'one'
 
-      # As of act v1.13.0 this fails for real (before it pretended to work but did not)
-      # - name: hashFiles
-      #   run: |
-      #     set -x
-      #     hash="bd52020371c038c4ad38a8d2df05dfa1a220d40fbe1ae83b63d6010cb527e531"
-      #     test "${{ hashFiles('actions/example-expression/.forgejo/fileone.txt') }}" = $hash
-      #     test "${{ hashFiles('actions/example-expression/.forgejo/fileone.*') }}" = $hash
+      - uses: actions/checkout@v4
+
+      - name: hashFiles
+        run: |
+          set -x
+          hash="aea6ca2329c852f5b480ec35e1fe09d39a6bd1b50f4f9cc38fbd4fef870dc107"
+          test "${{ hashFiles('.forgejo/fileone.txt') }}" = $hash
+          test "${{ hashFiles('.forgejo/fileone.*') }}" = $hash