Bump bootstrap in /New/Demos/Linq2TwitterDemos_MVCOld
Bump bootstrap in /New/Demos/Linq2TwitterDemos_MVCOld

Bumps bootstrap from 3.4.1 to 4.3.1.

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
JoeMayo/LinqToTwitter