Switch to Verilator 5 and update other dependencies

[RickLuiken]

Fixes #6 and #75.

I changed the way the Makefile works to compile both the sv and c++ files with verilator. Moreover, I did the following:

• Added a no-timing flag to the verilator command
• Changed the c++ std from c++14 to c++20 (recommended by verilator)
• Changed the spike fesvr version to a more recent one to support GCC13 (see this PR). Unfortunately, this newer version requires at least c++17, which is not compatible with verilator 4. Therefore, verilator 4 does not work with this PR!
• Updated the dockerfile. It now uses ubuntu 22.04. It builds verilator 5.006 from the source and now uses the same verible version as the CI.

To test it, I did the following:

• Run verilator tests using docker
• Run banshee tests using docker

I do not have access to modelsim, so I couldn't test that.

If you have any comments/questions, please let me know!

[RickLuiken]

Hi, just to let you know, the CI failed because it uses the old container with verilator 4. It should work if the new container is used, but I don't know how to test this in the CI. Could you help me with this?

[colluca]

Thanks for the contribution @RickLuiken.

We currently have an issue with the CI which we are solving. After that I will try it out with the Docker container update and let you know.

Best,
Luca

[colluca]

Hi @RickLuiken, once again thanks for the contribution. I reduced the changes and split them into two separate PRs, one of which has already been merged.

I will close this PR in favour of #158 where we will follow on the upgrade to Verilator 5.

Best,
Luca