[Config]: Add a .nvmrc file to standardize the Node version

[Aditya948351]

To prevent contributors from running into unsupported Node version errors, we should add a .nvmrc file to the root of the repository that explicitly specifies the Node version this project uses e.g. v20.

[github-actions]

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@Aditya948351, @Aditya948351 or @devpathindcommunity-india will review this and assign you this issue ASAP by checking if it is really needed for the website.