Use git tags when GitHub API returns an empty list of releases

[eramongodb]

Ongoing GitHub API issues appear to have revealed a potential script bug in mongosh_dl.py where a call to _get_latest_version() may return None, e.g.:

INFO Downloading mongosh... INFO Download latest mongosh for linux-x86_64 INFO Download url: https://downloads.mongodb.com/compass/mongosh-None-linux-x64.tgz ERROR Failed to download [https://downloads.mongodb.com/compass/mongosh-None-linux-x64.tgz] 

The only way I see _get_latest_version() can return None (when not taking the _get_latest_version_git() branch) is if the for item in data loop falls-through to the end of the function. I do not know what the response could be such that the API request succeeds (otherwise urllib.request.urlopen() should raise an URLError) and returns valid JSON (otherwise json.loads() should raise an JSONDecodeError), yet the contents do not contain any array element with a tag_name (or possibly does not contain any array elements at all...?). Therefore, this PR proposes printing the contents of data on error to assist with debugging this condition if it occurs again + raising an exception to fail-early when no tag_name is found (avoid attempting to download+cache an invalid URL).

[eramongodb]

It looks like GitHub Actions encountered the error:

RuntimeError: Could not find tag name in releases: [] 

This means the GitHub API request is "succeeding" by returning an empty JSON array...? I now wonder if json.loads() may be obsuring details in the raw response rather than actually being an empty JSON array. (Added a LOGGER.debug() call to capture the raw response for future inspection.)

Updated the proposed PR changes to perform a "length" check via conversion to bool (only JSON values of non-zero int, non-zero float, non-empty string, or true will incorrectly fail the check; such cases would mean the GitHub API is behaving even more strangely than it already is). The search for tag_name is moved into the try-catch block so that it can reuse the fallback to git tags.