Possibly suppress warnings about open client in `SPARQLWrapper.queries`

[lu-pl]

The SPARQLWrapper.queries method is a sync wrapper around async code and intended to be a convenience method for users how wish to execute multiple operations concurrently but do not want to write async code themselves.

SPARQLWrapper.queries internally creates a SPARQLWrapper instance with a shared httpx.AsyncClient that is then used in an async context manger for calls to SPARQLWrapper.aquery.

SPARQLWrapper.queries ergo is a managed application of SPARQLWrapper.aquery that uses the context manager API of SPARQLWrapper internally.

This application causes the sparqlx ClientManager to emit a warning about an open client though. While this is actually intended behavior, it is superfluos and potentially misleading for SPARQLWrapper.queries which actually manages the client through the context manager.

It is therefore preferable to suppress client warnings for SPARQLWrapper.queries.

[lu-pl]

Regarding the implementation in #127: The solution uses an async/sync context manager wrapper around warnings.catch_warnings and a relatively specific context filter.

Note: warnings.catch_warnings is not concurrency-safe, see Concurrent safety of Context Managers in the warnings docs.

Although the implemented change uses a contextlib.contextmanager which closures context state and can ergo mitigate concurrency safety problems, warnings filters are global and would actually need explicit locking or protection from a ContextVar.

In the case at hand, this is of no concern however, since SPARQLWrapper.queries controls its own encapsulated event loop.

[lu-pl]

Note: I was hesitant to implement the warnings suppression just for SPARQLWrapper.queries because the case may be made that warnings should be suppressed for the SPARQLWrapper context manager as well.

For now, suppressing warnings just for SPARQLWrapper.queries seems a passable solution to me though. SPARQLWrapper.queries is an application of SPARQLWrapper and also shows how the class may be used, so suppressing the warnings in SPARQLWrapper.queries can be seen as an example application of a warnings filter for sparqlx.