Deploying v53 (and bumping version to v54)

[garbas]

This Pull Request contains the version bump and should be merged once deployment is successful.
Deployment coordinator for this release is: @catlee

Deployment to staging

• Build1 -> https://tools.taskcluster.net/groups/F_7VTD_ORzy8HexA0BD5Cw
• Build2 -> https://tools.taskcluster.net/groups/QGxI9ZYSSMm6I0wYo9a9-A

Verifications

• docs
• codecoverage/backend
• codecoverage/bot
• codecoverage/crawler
• pulselistener
• releng-frontend
• mapper/api
• notification/identity
• notification/policy
• tokens/api
• tooltool/api
• treestatus/api
• shipit/api
• shipit/frontend
• staticanalysis/bot
• staticanalysis/frontend
• uplift/backend
• uplift/bot

Deployment to production

• Build1 -> https://tools.taskcluster.net/groups/Ijtz5ccwQjuFxpkCmnB5zQ

Verifications

• docs
• codecoverage/backend
• codecoverage/bot
• codecoverage/crawler
• pulselistener
• releng-frontend
• mapper/api
• notification/identity
• notification/policy
• tokens/api
• tooltool/api
• treestatus/api
• shipit/api
• shipit/frontend
• staticanalysis/bot
• staticanalysis/frontend
• uplift/backend
• uplift/bot