Remove username entity from Geocaching

[frenck]

Proposed change

Removes the username entity from the Geocaching integration.
It's rather static and a bit of an odd one. We generally don't expose account names as entities.

It's not a breaking change that affects people, as it has not yet landed in beta/stable yet.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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• This PR fixes or closes issue: fixes #
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[probot-home-assistant]

Hey there @Sholofly, @reinder83, mind taking a look at this pull request as it has been labeled with an integration (geocaching) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[reinder83]

Looks good to me, the username is not really interesting anyway