Add method to release the contained interface

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[x] Check that you've added documentation to any new methods
[x] Rebase from master if you're not already up to date
[ ] Add or modify an example if there are changes to the public API
[x] Add a CHANGELOG.md entry in the Unreleased section under the appropriate heading (Added, Fixed, Changed, etc)
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PR description

Just a method that consumes the Ssd1306 and returns the contained interface.