v7.3.1

Changes:

• Remove PHP 7.3 from tests
• Simplify Title::soundtrack() to just return raw data rather than badly trying to parse it

Bug fixes:

• Fix Calendar::upcomingReleases()
• Fix PersonSearch::results()
• Fix Title::storyline()
• Fix Title::tagline()
• Fix Title::parentalGuide()
• Fix TitleSearch::search()
• Fix Title::populateEpisodeSeasonEpisode()
• Fix Title::keywords() #278 @duck7000 and @tboothman
• Fix Person::spouse() #275 @duck7000
• Fix Title::died()