Bump src/cf-mysql-broker

Bump cloudfoundry/cf-mysql-broker:
  alex choi:
     forgot a failing test ( Travis Success: https://travis-ci.org/cloudfoundry/cf-mysql-broker/builds/15739332 )
     Adding long description to mysql broker catalog ( Travis Failed: https://travis-ci.org/cloudfoundry/cf-mysql-broker/builds/15739265 )
Adding long_description text

[#48629153]