OperationalError: cannot VACUUM from within a transaction

[chapmanjacobd]

Maybe when calling .vacuum() and other DB-level write-lock operations sqlite_utils could guard against this error message by automatically committing first?

     46 db["media"].optimize()  # type: ignore
---> 47 db.vacuum()

File ~/.local/lib/python3.10/site-packages/sqlite_utils/db.py:1047, in Database.vacuum(self)
   1045 def vacuum(self):
   1046     "Run a SQLite ``VACUUM`` against the database."
-> 1047     self.execute("VACUUM;")

File ~/.local/lib/python3.10/site-packages/sqlite_utils/db.py:470, in Database.execute(self, sql, parameters)
    468     return self.conn.execute(sql, parameters)
    469 else:
--> 470     return self.conn.execute(sql)

OperationalError: cannot VACUUM from within a transaction

It might also be nice to add a sentence or two about how transactions are committed on the docs page. When I was swapping out my sqlite3 code for this library it was nice that everything was pretty much drop-in but I was/am unsure what to do about the places I explicitly call .commit() in my code

Related to #121