Reduce entropy of quotations s/'/"/g

Variety of quotes used in the file, even in the same sections.

Arbitrarily proposing to go with " (either is permissible) to adhere to style guide on sticking with one of the quoting options:

https: //google.github.io/styleguide/pyguide.html
Change-Id: I5080c25262920dffe5eeea89583b88eb161f34a7