Add libsecret to the conatiner for cargo authentication

[Black616Angel]

Currently under debian no further libraries are installed due to the mostly sufficient use of the buildpack-deps and alpine only installs very few of them, but for the usage of cargo to upload compiled libraries or download dependencies from other registries with credentials, libsecret is needed.

So I think, that it would be beneficial for a lot of cases, if the library would be included in all the images.