MAINTENANCE: Automated closing of pull requests.

This commit exists to close the following pull requests on Github:

Closes apache#1767 (close requested by 'andrewor14')
Closes apache#6952 (close requested by 'andrewor14')
Closes apache#7051 (close requested by 'andrewor14')
Closes apache#5357 (close requested by 'marmbrus')
Closes apache#5233 (close requested by 'andrewor14')
Closes apache#6930 (close requested by 'JoshRosen')
Closes apache#5502 (close requested by 'andrewor14')
Closes apache#6778 (close requested by 'andrewor14')
Closes apache#7006 (close requested by 'andrewor14')