Idea: Optional cached .deb install path to speed up Linux installs

[AlexanderLanin]

Is your feature request related to a problem? Please describe.
Installing Graphviz via apt-get install on GitHub-hosted Linux runners is quite slow (~80 seconds).
Since runners are ephemeral, this install happens on every run and adds noticeable overhead.

Describe the solution you'd like
Add an optional opt-in faster install path:

• download Graphviz .deb files + dependencies manually
• cache them via actions/cache
• install via dpkg -i + apt-get -f install

This would apply to Linux runners only, and most likely only for a small set of supported versions (e.g. specific Ubuntu versions, Graphviz versions).
Default behavior would stay unchanged — the faster path would only be used if explicitly enabled.

Describe alternatives you've considered

• Doing it directly in my repo / maintaining a separate Action just for optimized Graphviz install (but it makes more sense to improve this existing Action).
• Using a full container image with Graphviz preinstalled.

Additional context
Installing from cached .deb files could potentially save additional time during CI runs.
I have not tested this yet.

Before investing time into a PR, I’d like to check if you would be open to such an addition.

Thanks for this great Action!