Add proxy for autocommit property on Connection

[jonathan-d-zhang]

Description

Add a proxy property for the autocommit property on sqlite3.Connection objects.

Use Case

I want autocommit=False as suggested by the sqlite3 docs (see docs). I also want to set PRAGMA journal_mode = WAL. The issue is that I can't change the journal_mode when in a transaction, which is always the case when autocommit=False. So the solution is to set the autocommit property after setting the journal_mode. This works fine in sqlite3, but aiosqlite doesn't have the property.

I can work around this by simply reaching into the aiosqlite.Connection object and accessing the _conn attribute, but this is clearly not ideal.

[amyreese]

Looks like this is a new feature in sqlite for Python 3.12. Can you update this to raise an exception accordingly so that mypy passes cleanly? Also, a simple test case would be appreciated (and I'd be ok with something like @skipIf(sys.version_info < (3,12))).

[amyreese]

Mypy fails because this is a 3.12 feature:

python -m mypy -p aiosqlite
aiosqlite/core.py:246: error: "Connection" has no attribute "autocommit"  [attr-defined]
Found 1 error in 1 file (checked 10 source files)