readme: ubuntu dependencies

[hypergig]

• adding libspdlog-dev to list of ubuntu dependencies
• making list easier to read and copy from
• sorting (ocd)

This morning my build failed on master. I noticed a bunch of these errors:

../subprojects/spdlog-1.3.1/include/spdlog/details/pattern_formatter.h:99:9: error: ‘assert’ was not declared in this scope

Also meson --reconfigure build was saying:

Run-time dependency spdlog found: NO (tried pkgconfig and cmake)
Looking for a fallback subproject for the dependency spdlog

Installing libspdlog-dev seemed to fix it.

[Alexays]

Thanks!