docker-compose.yml: fix flyway SSL warning
docker-compose.yml: fix flyway SSL warning

The Connector/J JDBC driver connects to the database over SSL by
default. Since we are not using SSL, disable it.

This fixes the following (verbose) warning when running the
flyway service:

WARN: Establishing SSL connection without server's identity
verification is not recommended. According to MySQL 5.5.45+, 5.6.26+
and 5.7.6+ requirements SSL connection must be established by default
if explicit option isn't set. For compliance with existing applications
not using SSL the verifyServerCertificate property is set to 'false'.
You need either to explicitly disable SSL by setting useSSL=false, or
set useSSL=true and provide truststore for server certificate
verification.

smrealms/smr,smrealms/smr,hemberger/smr,hemberger/smr,hemberger/smr,smrealms/smr,hemberger/smr