PMM-14906 Basic version cache.

[JiriCtvrtka]

https://jira.percona.com/browse/PMM-14906

PMM PR: percona/postgres_exporter#387

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4332-9e35c83
Client docker: perconalab/pmm-client-fb:PR-4332-9e35c83
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4332-9e35c83
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4332-9e35c83.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4332-9e35c83&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4332-9e35c83.tar.gz

[JNKPercona]

API tests have failed: https://pmm.cd.percona.com/job/pmm3-api-tests/5961/

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4332-9b2dd44
Client docker: perconalab/pmm-client-fb:PR-4332-9b2dd44
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4332-9b2dd44
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4332-9b2dd44.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4332-9b2dd44&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4332-9b2dd44.tar.gz

[JNKPercona]

API tests have succeded: https://pmm.cd.percona.com/job/pmm3-api-tests/5966/