cli: release 3.19.1

[bassosimone]

The objective of this release is to include the signal fix ooni/probe-cli#1389 plus other minimal work to update geoip databases etc. We'll merge to master first, then backport to the release branch and tag a release.

• merge Update signal test endpoints fixes probe/2627 probe-cli#1389
• merge chore: update signal test description to test v0.2.3 spec#281
• backport Update signal test endpoints fixes probe/2627 probe-cli#1389:
• probe-cli: update bundled certs (using go generate ./...): done, no changes!
• probe-cli: update github.com/ooni/probe-assets dependency
• probe-cli: make sure all workflows are green
• probe-cli: go test -race -count 1 ./... must pass locally
• probe-cli: tag a new version
• probe-cli: update internal/version/version.go
• android: publish packages
• iThena: notify about new release
• debian: publish packages

[bassosimone]

Done!