Upgrade jQuery to 3.3.1 as per Tipue 7.0 requirements.
Upgrade jQuery to 3.3.1 as per Tipue 7.0 requirements.

Cherry picked from commit
getpelican/pelican-themes@6ad5e53087538fb4d8e119ab2ab49dad37970726.

StevenMaude/pelican-bootstrap3-sm,StevenMaude/pelican-bootstrap3-sm