get_file_content: catch only 404, raise everything else
Just spent some time debugging an issue where packit.yaml was not found while being 100 % it's in there.

It turned out that my token was incorrect and github kept throwing 401: that should bubble up, we should catch 404 only. 
diff --git a/ogr/services/github.py b/ogr/services/github.py
index cfbecf1..34625ae 100644
--- a/ogr/services/github.py
+++ b/ogr/services/github.py
@@ -453,7 +453,7 @@ class GithubProject(BaseGitProject):
             return self.github_repo.get_contents(
                 path=path, ref=ref
             ).decoded_content.decode()
-        except Exception as ex:
+        except UnknownObjectException as ex:
             raise FileNotFoundError(f"File '{path}' on {ref} not found", ex)
 
     @staticmethod
['ogr/services/github.py']