Format API keys in hexa instead of base64

[ManyTheFish]

This PR:

• Changes API key generation and formatting to ease the generation of the key made by our users
• updates the uuid crate version

The API key can now be generated in bash as below:

echo -n $HYPHENATED_UUID | openssl dgst -sha256 -hmac $MASTER_KEY

fixes the issue raised in product/discussion#421, this should not impact anything in documentation nor integration but ease the key generation on the user sides.

poke @gmourier

[Kerollmops]

Thank you very much! I am just awaiting @gmourier approval. Would it be possible to update the specs too @ManyTheFish?

This PR is directly related to this comment. It makes it possible for the users to generate the keys on their side, in a determinist way. I would like to inform the @meilisearch/integration-team and @meilisearch/docs-team, of these changes. However, if you didn't document this client-side key generation (by using hmac and base64...) you must ignore this message. if you are displaying the content of the key field, note that we changed the encoding function and display a 64 chars hexadecimal lowercase string instead of a smaller base64 encoded string.

[gmourier]

@meilisearch/docs-team @meilisearch/integration-team

Know that the representation of a key field value changes since it removes the base64 encoding.

Now -> key: f8f4d6bcaf27b0308c9ccd30a25e385bdc6a25838ead081a69dbcbc374172bb1 (hexadecimal format)
Before -> key: JTvtex9QQsqanj6cke3hfkqeNIlnHa280YtYIbU/G7Y= (base64 format)

I think you may want to update code snippets or examples showing a key value. At least at some point!

[Kerollmops]

bors merge

[bors]

🕐 Waiting for PR status (Github check) to be set, probably by CI. Bors will automatically try to run when all required PR statuses are set.

[curquiza]

bors merge

[bors]

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[bors]

Build succeeded:

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• Run Rustfmt
• Run tests in debug
• Tests on macos-latest
• Tests on ubuntu-18.04
• Tests on windows-latest