Run sqlite-utils query in a transaction so that DML is committed

The failing test I added in the previous commit now passes.

Diff best viewed with whitespace ignored (git diff/show -w), as most of
the change is indentation for the new "with" block.

sqlite_utils/cli.py

@@ -669,24 +669,25 @@ def drop_view(path, view):
 def query(path, sql, nl, arrays, csv, no_headers, table, fmt, json_cols):
     "Execute SQL query and return the results as JSON"
     db = sqlite_utils.Database(path)
-    cursor = db.conn.execute(sql)
-    if cursor.description is None:
-        # This was an update/insert
-        headers = ["rows_affected"]
-        cursor = [[cursor.rowcount]]
-    else:
-        headers = [c[0] for c in cursor.description]
-    if table:
-        print(tabulate.tabulate(list(cursor), headers=headers, tablefmt=fmt))
-    elif csv:
-        writer = csv_std.writer(sys.stdout)
-        if not no_headers:
-            writer.writerow(headers)
-        for row in cursor:
-            writer.writerow(row)
-    else:
-        for line in output_rows(cursor, headers, nl, arrays, json_cols):
-            click.echo(line)
+    with db.conn:
+        cursor = db.conn.execute(sql)
+        if cursor.description is None:
+            # This was an update/insert
+            headers = ["rows_affected"]
+            cursor = [[cursor.rowcount]]
+        else:
+            headers = [c[0] for c in cursor.description]
+        if table:
+            print(tabulate.tabulate(list(cursor), headers=headers, tablefmt=fmt))
+        elif csv:
+            writer = csv_std.writer(sys.stdout)
+            if not no_headers:
+                writer.writerow(headers)
+            for row in cursor:
+                writer.writerow(row)
+        else:
+            for line in output_rows(cursor, headers, nl, arrays, json_cols):
+                click.echo(line)
 
 
 @cli.command()