mrhlpr: mr: use a simpler mechanism to detect if user approved a MR

This doesn't depend on an auth error to detect if a user has approved a
MR, and fixes #24.

For some reason mr.approval_state().get was 404'ing, causing #24.

mrhlpr/mr.py

@@ -549,16 +549,14 @@ def finish(
     if skip_approve or (gl.user and mr.author and gl.user.id == mr.author.get("id")):
         print("Skipping approval...")
     else:
-        print("Approving MR...")
-        try:
-            mr.approve(git.sha())
-        # For some reason, approve fails with auth error if already approved...
-        except gitlab_api.GitlabAuthenticationError as e:
-            approved_by_ids = [ap["id"] for ap in mr.approval_state.get().rules[0]["approved_by"]]
-            if gl.user is None:
-                raise e
-            if gl.user.id not in approved_by_ids:
-                raise RuntimeError("Approving failed, and MR not yet approved") from e
+        if mr.approvals.get().attributes["user_has_approved"]:
+            print("MR has already been approved by you!")
+        else:
+            print("Approving MR...")
+            try:
+                mr.approve(git.sha())
+            except Exception as e:
+                raise RuntimeError("Approval failed, your approval was not added!") from e
 
     if comment:
         print("Adding the comment...")