:memo: Updated the deprecated code in off-chain storage tutorial and file

[LuffySama-Dev]

Hi @barriebyron ,

I am creating this PR to resolve the issue number #756 . The tutorial has multiple errors, I have asked in discord https://discord.com/channels/484437221055922177/1210453122376269935

Waiting for the resolution. Meanwhile I have updated the deprecated code.

Thank You 😃

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