Remove unused Log::Dispatch dependency

[ehuelsmann]

Description

Nothing uses Log::Dispatch, so it seems only appropriate to remove it from the dependency list.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project, please see the contribution guidelines.
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes

[coveralls]

Coverage remained the same at 79.053% when pulling 61712ff on ehuelsmann:rm-unused-log-dispatch into b702188 on jonasbn:master.

[jonasbn]

I wonder how that got in there, nicely spotted