Improve retry mechanism (#194) (#194)

When a ChunkedEncodingError occurs, request and response are not set and there is no way to get the URL that causes the error.
With this change all URLs are retried. The max_retries parameter is decreased each time so that we do not get stuck in an infinite loop.

I also considered to also wait before retrying, but for now I don't see any benefit to it.

Relates to #188.

src/unity.py

@@ -33,6 +33,8 @@ print(f"::group::{PRODUCT}")
 all_versions = {}
 next_page_url = URL
 
+# Do not try to fetch multiple pages in parallel: it is raising a lot of ChunkedEncodingErrors and
+# make the overall process slower.
 while next_page_url:
     next_page_url = fetch_releases(all_versions, next_page_url)