chore: remove peer deps

[achingbrain]

We added peer deps to signal to the user that they should add the modules they depend on as deps of their project.

Starting with npm7 all peer deps get installed automatically which defeats the purpose of our use of peer deps, so let's remove them.

[achingbrain]

It also means you can't test rcs of libp2p without getting this error:

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! While resolving: js-ipfs@1.0.0
npm ERR! Found: libp2p@0.31.0-rc.0
npm ERR! node_modules/libp2p
npm ERR!   libp2p@"0.31.0-rc.0" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer libp2p@"^0.30.0" from libp2p-floodsub@0.25.0
npm ERR! node_modules/libp2p-floodsub
npm ERR!   libp2p-floodsub@"^0.25.0" from the root project

[vasco-santos]

We need to get #113 in and change we handle this. I will try to prioritize that work.