deps: remove undocumented fossil syntax
deps: remove undocumented fossil syntax

As discussed with Martin Schut, remove support for
{app_name, "vsn", {fossil, "url", latest}.

walrusVision/rebar3,rebar/rebar3,blt/rebar3,jacktang/rebar,scatterbrain/rebar,paulo-ferraz-oliveira/rebar,dcarastan/rebar,choptastic/rebar,rebar/rebar,processone/rebar3,linearregression/rebar3,platinumthinker/rebar,CMoH/rebar,bsmr-erlang/rebar,vladdu/rebar3,shkumagai/rebar,K2InformaticsGmbH/rebar,csyangchen/rebar,apache/couchdb-rebar,lrascao/rebar,benoitc/rebar3,K2InformaticsGmbH/rebar,macintux/rebar,scatterbrain/rebar,bsmr-erlang/rebar,beni55/rebar,rebar/rebar,K2InformaticsGmbH/rebar,evnix/rebar,surik/rebar3,lpgauth/rebar,linearregression/rebar3,sile/rebar3,matwey/rebar,K2InformaticsGmbH/rebar,norton/rebar,project-fifo/rebar3,dcarastan/rebar,jacktang/rebar,fauxsoup/rebar3,lrascao/rebar,syl20bnr/rebar,csyangchen/rebar,matwey/rebar,walrusVision/rebar3,evnix/rebar,oubiwann/rebar,matwey/rebar,GabrielNicolasAvellaneda/rebar,oubiwann/rebar,SiDen/rebar,GabrielNicolasAvellaneda/rebar,project-fifo/rebar3,fishcakez/rebar3,lrascao/rebar3,RubberCthulhu/rebar,apache/couchdb-rebar,shkumagai/rebar,platinumthinker/rebar,cloudant/couchdb-rebar,beni55/rebar,jacktang/rebar,norton/rebar,lpgauth/rebar,erlang/rebar3,scatterbrain/rebar,evnix/rebar,lrascao/rebar,rebar/rebar,fabiankrol/rebar3,choptastic/rebar,choptastic/rebar,K2InformaticsGmbH/rebar,platinumthinker/rebar,fauxsoup/rebar3,saleyn/rebar3,norton/rebar,beni55/rebar,jbalint/rebar3,djnym/rebar3,rebar/rebar3,macintux/rebar,jbalint/rebar3,matwey/rebar,processone/rebar3,CMoH/rebar,CMoH/rebar,heroku/rebar,lpgauth/rebar,csyangchen/rebar,blt/rebar3,syl20bnr/rebar,matwey/rebar,oubiwann/rebar,ferd/rebar3,fabiankrol/rebar3,bsmr-erlang/rebar,surik/rebar3,dcarastan/rebar,sile/rebar3,cloudant/couchdb-rebar,shkumagai/rebar,norton/rebar,lrascao/rebar,apache/couchdb-rebar,GabrielNicolasAvellaneda/rebar,RubberCthulhu/rebar,SiDen/rebar,zugolosian/rebar3,paulo-ferraz-oliveira/rebar,zugolosian/rebar3,lrascao/rebar,bsmr-erlang/rebar,kellymclaughlin/rebar3,syl20bnr/rebar,heroku/rebar,tsloughter/rebar3,macintux/rebar,benoitc/rebar3,norton/rebar3,cloudant/couchdb-rebar,SiDen/rebar,paulo-ferraz-oliveira/rebar