Automatically append the OS architecture to the cache key

[mitesch]

We had a user report as part of our Ubuntu arm64 rollout that tracked back to the apt package cache accidentally being shared between the x64 runners and arm64 runners. This resulted in some odd errors.

https://github.com/community/maintainers/discussions/480#discussioncomment-12206804

This change will add the CPU architecture to the key to be hashed.

I am not adding it if it is current "normal" case of x86_64 for ubuntu-latest, ubuntu-24.04, and ubuntu-22.04 in an effort to not needlessly invalidate caches.

Logs from ubuntu-latest

Normalizing package list...
done
Validating action arguments (version='', packages='libfuse2=2.9.9-5ubuntu3 libqcustomplot-dev=2.0.1+dfsg1-5 libqscintilla2-qt5-dev=2.11.6+dfsg-4 libqt5svg5=5.15.3-1 ninja-build=1.10.1-1 qttools5-dev=5.15.3-1')...
done
Creating cache key...
- CPU architecture is 'x86_64'.
- Value to hash is 'libfuse2=2.9.9-5ubuntu3 libqcustomplot-dev=2.0.1+dfsg1-5 libqscintilla2-qt5-dev=2.11.6+dfsg-4 libqt5svg5=5.15.3-1 ninja-build=1.10.1-1 qttools5-dev=5.15.3-1 @  3'.
- Value hashed as '7249e230c6406f49de3a7775bbe7ded2'.
done
Hash value written to /home/runner/cache-apt-pkgs/cache_key.md5
Run actions/cache/restore@v4
  
Cache not found for input keys: cache-apt-pkgs_7249e230c6406f49de3a7775bbe7ded2
Run ${GITHUB_ACTION_PATH}/post_cache_action.sh \
  
Updating APT package list...
done

Logs from ubuntu-24.04-arm

Normalizing package list...
done
Validating action arguments (version='', packages='libfuse2=2.9.9-5ubuntu3 libqcustomplot-dev=2.0.1+dfsg1-5 libqscintilla2-qt5-dev=2.11.6+dfsg-4 libqt5svg5=5.15.3-1 ninja-build=1.10.1-1 qttools5-dev=5.15.3-1')...
done
Creating cache key...
- CPU architecture is 'aarch64'.
- Architecture 'aarch64' added to value.
- Value to hash is 'libfuse2=2.9.9-5ubuntu3 libqcustomplot-dev=2.0.1+dfsg1-5 libqscintilla2-qt5-dev=2.11.6+dfsg-4 libqt5svg5=5.15.3-1 ninja-build=1.10.1-1 qttools5-dev=5.15.3-1 @  3 aarch64'.
- Value hashed as '62b41aa5465640843bc389516657d8f0'.
done
Hash value written to /home/runner/cache-apt-pkgs/cache_key.md5
Run actions/cache/restore@v4
Cache not found for input keys: cache-apt-pkgs_62b41aa5465640843bc389516657d8f0
Run ${GITHUB_ACTION_PATH}/post_cache_action.sh \
Updating APT package list...
done

[mitesch]

https://github.com/mitesch/sqlitebrowser/actions/runs/13419146946

Here's an example run using my branch