Release 2.53.x

[uhlissuh]

• Create 2.54.0 Milestone (due date one week from now)
• Move all open tickets in 2.53.0 to 2.54.0
• Close 2.53.0 Milestone
• Pull master
• Ensure make check passes
• git tag v2.53.0; git push --tags
• Create release entry in https://github.com/mozilla/experimenter/releases/
• @here deploying experimenter v2.53.0 https://github.com/mozilla/experimenter/milestone/103?closed=1 to stage in #experimenter
• Quickly verify that stage loads with v2.53.x
• @robotblake please push experimenter v2.53.x to production in #experimenter
• Verify that prod loads with v2.53.x
• Merge all dependabot prs by:
  • Approve each dependabot pr with the message @dependabot squash and merge
  • They will automatically re run CI and merge when done without supervision
• Create release issue for Release v2.54.x