Fix: race condition prevents openuem-certs to generate the certificates

[doncicuto]

As reported by Roman in Discord, when you try to launch the docker compose up -d command in Windows, the openuem-certs container throws an error

... generating your CA certificate and private keys
... creating your  CA certificate
... saving your CA certificate to /certificates/ca/ca.cer
... open /certificates/ca/ca.cer: is a directory

It seems that the docker compose file is not defining properly, how the certificates folder can be shared between the services. Looks that one of the services that requires certificates, creates empty folders as the paths to the certificates don't exist, and then when openuem-certs tries to generate the files, it cannot as there are existing folders.

We need to find a way to improve the compose file using a certificates named volume

As a workaround, the docker compose up openuem-certs -d command can be run first to generate the files.