update versions in readme examples

[johnduffell]

Just noticed that the readme is pointing at a version of logback with a high severity vulnerability, so I've just bumped the version to a safer one.

[SethTisue]

Just to check — you've verified that the newer version actually works in this context...?

[johnduffell]

Yes we are using it with no issues e.g. https://github.com/guardian/members-data-api/blob/a5bb9b3576536f362c144690712ac8922a943e47/project/Dependencies.scala#L30

although having said that intellij is letting me know that 1.5.6 is out by now!

[johnduffell]

I've added another change to make the compile use that version too, as it makes no sense for me to leave it inconsistent.

[SethTisue]

@johnduffell so this now incorporates #432 ?

I can't approve this one or 432, the other maintainers need to make a choice here.

[jxnu-liguobin]

Thank you, this is redundant and will be resolved once #432 is merged.