Add timeout to pypi version request, preventing undue hangups on startup

[ntjess]

Fixes #853

[maartenbreddels]

We thought a bit about it. What do you think of this solution? Where we only show it if we found a new version on time.

[ntjess]

Have you tested the timing between the browser opening and the message being printed in the console?

My only concern with this new approach is the following scenario:

• User runs solara run ...
• Browser window opens, user no longer thinks about their terminal
• Upgrade message prints, but user never sees it because their focus is already on the browser
• App generates print() / logging statements that obfuscate the upgrade message
• User never learns there is a solara update

[ntjess]

Another thought: We may also want to read the pip conf (through an approach like pip config list -> check if index-url is overwritten) to see which URL should be hit instead of defaulting to pypi.

This is a more robust solution than just a timeout, and would work for e.g. private pypi setups like artifactory. However, it is nontrivial to know ahead of time where pip will fetch from (overloads at global/user level, even per-pip command). So maybe the complexity outweighs the benefits.