Fix up CI actions

This pull-request has several updates to address failing CI actions:

1. ci / Verilator Lint: needs Verilator-5.008 or newer to handle "pound delays" in the PLL models. However, there currently is no simple apt install install verilator command that fetches and installs anything newer than v4.100. Recommend we keep this action, and WAIVE it for now.
2. lint / Format Verilog Sources: the runs-on parameter was set to ubuntu 18.04 which GitHub no longer supports. Passing now.
3. lint / Vendor Up-to-Date: passing.
4. lint / Doc Up-to-Date: depreciated as this repo no longer supports auto-generated documentation.
5. lint / YamlFmt: depreciated as this check is no longer required as the connection to sub-modules was deliberately severed.
6. xsim_options is no long recognised by fusesoc (was it ever?).