Make it possible to specify the parser for BeautifulSoup4

[fumiya5863]

If you have lxml installed, BeautifulSoup4 will set lxml as the default parser, so it would be better to be able to specify the parser depending on the situation. https://github.com/erikriver/opengraph/blob/e2322563004c923a4c1ce136733a44efe5fc8caa/opengraph/opengraph.py#L63 This is the default setting because we didn't actually do the parser above.

Depending on the environment, the following issue cases may occur due to the above reasons https://github.com/erikriver/opengraph/issues/37

As a solution, I think it would be a good idea to add a new parser that can be selected in the following arguments https://github.com/erikriver/opengraph/blob/e2322563004c923a4c1ce136733a44efe5fc8caa/opengraph/opengraph.py#L28