Minor workflow simplifications

[TSRBerry]

This PR is a follow up from DarkMatterCore/libusbhsfs#29 and simplifies the existing workflow a tiny bit.

I told you about some improvements quite a while ago and never got around to PR them. It seems someone else also found improvements, so the changes I made aren't as significant.

Some notes about the changes I made:

• The check to skip a workflow run can be omitted, since this can already be done without that.
  See: Skipping workflow runs
• Earlier I also opened a PR for the docker images from dkp (Add dkp-toolchain-vars package to docker images devkitPro/docker#28) to include the dkp-toolchain-vars package as well.
  If that PR gets accepted the last dkp-pacman line can also be removed which I'll do in a new PR.

A few other improvements that could be made, but I didn't want to include here:

• Using ccache with GitHub Actions cache to speed up compilations (like ldn_mitm)
• Using releases for libusbhsfs and installing them in the workflow instead of compiling it there
• Using the libnx library that's already present in the dkp image and falling back to the latest commit if the first build attempt fails (similar to ldn_mitm)

Workflow run using my libusbhsfs changes: https://github.com/TSRBerry/nxdumptool/actions/runs/6709816685/job/18233685461
Although it fails in the end this seems to be unrelated to my changes.

[DarkMatterCore]

Thanks! I'll take a better look at this after I get back home.

[DarkMatterCore]

Looks good to me. Thanks again. :)