Thanks for the work, but we don't generally make bulk changes like this.  It generates churn in the codebase, and has the risk of inadvertently changing the meaning of the tests, to little actual benefit.  Instead we modernize tests when we touch them for other reasons and are in a position to confirm that the changes do not change the meaning of the tests.  (I realize that for most of your changes the meaning is trivially preserved...but when you make a lot of changes you are almost certain to make some mistakes...thus the resistance to doing bulk updates.)