setup-dotnet defaulted to /usr/share/dotnet, which the runner user cannot write to (Permission denied). Point DOTNET_INSTALL_DIR at runner.tool_cache so the 8.0 SDK installs into a writable, cached location.
setup-dotnet defaulted to /usr/share/dotnet, which the runner user cannot write to (Permission denied). Point DOTNET_INSTALL_DIR at runner.tool_cache so the 8.0 SDK installs into a writable, cached location.