install_dependencies.sh: libunwind-dev install fails on GitHub-hosted Ubuntu 22.04 runners (both x64 and arm64)

On GitHub-hosted `ubuntu-22.04` and `ubuntu-22.04-arm` runners, `scripts/linux/ubuntu/install_dependencies.sh` fails at the "Ensuring latest libunwind-dev is installed..." step:

Ensuring latest libunwind-dev is installed...
E: Unable to correct problems, you have held broken packages.

The script continues past that point, but later fails for real once it tries to install `libgstreamer1.0-dev` (which depends on `libunwind-dev`):

Installing libgstreamer1.0-dev
E: Unable to correct problems, you have held broken packages.
error installing libgstreamer1.0-dev
...unmet dependencies: libgstreamer1.0-dev : Depends: libunwind-dev

Happens identically on both x64 and arm64 22.04 runners, so it's not architecture-specific - looks like something in the GitHub-hosted Ubuntu 22.04 runner image (possibly a pre-installed toolchain) is holding/pinning a conflicting libunwind package before this script runs. Ubuntu 24.04 runners aren't affected.

openframeworks/projectGenerator#645 added Ubuntu 22.04 (x64 and native arm64) legs to its CI, both of which hit this on first run:

• https://github.com/openframeworks/projectGenerator/actions/runs/32368714821/job/96424130411
• https://github.com/openframeworks/projectGenerator/actions/runs/32368714821/job/96424130379

Haven't dug into which package the runner image is holding yet - filing this mainly so it's tracked, will follow up if we find the exact conflicting package.