Try using the public github api if rpkg-api is down

[patrickvossler18]

At the time of writing, the rpkg-api is giving a 502 error. This PR catches the error and instead uses the public GitHub search API endpoint.

I am not very familiar with handling exceptions in R, so if there is a more elegant way to do this, please let me know.

[jimhester]

@gepuro is your rpkg-api service down permanently, or is this temporary?

[jimhester]

Can you please add a bullet to NEWS? It should briefly describe the change and end with (@yourname, #issuenumber).

[patrickvossler18]

Done, I used the issue #69 since I only submitted a PR. Is that ok?

[gepuro]

@jimhester
I restarted rpkg-api.gepuro.net .
For this system make stable, where can I get support ? I have some idea to do.

[patrickvossler18]

Hi @gepuro, I'd be happy to help try to make the rpkg-api more stable and get more familiar with Rust! My email is in my profile if you'd like to talk more about it.