Add expanduser to the path passed to stash restore action

Often when you want to upload cache, you are doing it from
the ~/.cache or similar directory. And you want to pass "~" rather
than path to the home directory. The original upload-artifact
and download-artifact are expanding the `~` to home dir, and
since "stash/save" uses direction "upload-artifact" it also accepts
the `~` prefix. However the "stash/restore" action uses gh
download and passes the path via environment variable, so bash
will not expand it. We need to manually expand user in the mung step

Author: potiuk

stash/restore/action.yml

@@ -78,7 +78,7 @@ runs:
         m.output_munged_name(output = 'stash_head')
         m.output_munged_name(ref = 'base_ref', output = 'stash_base')
         with open(os.environ['GITHUB_OUTPUT'], 'a') as f:
-          f.write(f'stash_path={os.path.abspath(os.environ["stash_path"])}' + '\n')
+          f.write(f'stash_path={os.path.abspath(os.path.expanduser(os.environ["stash_path"]))}' + '\n')
 
     - name: Check for stash artifact
       id: check-stash