Fix CMake for forked repos' CI runners

[Rainyan]

Description

Fix the build_info.cmake for forked repos' CI to ensure that tags from upstream are fetched before attempting to read them.

This seems to be a bug from #1487 since the commit previous to that merge works fine.

Error logs

From a failed GH runner in a fork:

 fatal: No names found, cannot describe anything.
-- GIT_LATESTTAG: 
CMake Error at cmake/build_info.cmake:23 (message):
  Failed to get git tag
Call Stack (most recent call first):
  CMakeLists.txt:19 (include)


-- Configuring incomplete, errors occurred!

Toolchain

N/A

Linked Issues

[AdamTadeusz]

it uuuh looks fine I guess?

[Rainyan]

it uuuh looks fine I guess?

Thanks for the confidence 🤣

To verify the bug:

• Doesn't work (CI has red mark of sadness): https://github.com/Rainyan/rebuild/tree/testing2
• Works (CI green check mark): https://github.com/Rainyan/rebuild/tree/testing

The difference between these two branches is having the commit 0352dc3 applied as the HEAD.

• And finally, after this PR is applied, we get the green check mark of happiness in the CI run again at: https://github.com/Rainyan/rebuild/tree/bug/ci-forked

If you want to reproduce it, enable the GitHub runner for your own fork, sync your fork's master to the upstream master, and watch the CI run explode.

But I'm no CMake master so if you or anyone else has opinions on a better way to fix this, then we could improve upon the fix later. Gonna merge this for now though.