GitHub's 60 requests per hour limit is hindering GithubPackageResolver

[Tyrrrz]

GitHub allows only up to 60 requests per hour from every IP when using their API without authentication. We can't use authentication because Onova is used in client-side apps, which will expose the private keys.
Currently, Onova makes 1 request to check for update and 1 more to download updates so 60/hr is more or less enough, however this limit is shared among everything coming from one IP so if the user has e.g. Octotree extension installed in their browser, they can very quickly exhaust this limit, making Onova unable to work.