feat(frontends/lean/parser): remove unnecessary restriction
feat(frontends/lean/parser): remove unnecessary restriction

leodemoura/lean,digama0/lean,leanprover/lean,fpvandoorn/lean,Kha/lean,fgdorais/lean,avigad/lean,leodemoura/lean,Kha/lean,leanprover-community/lean,rlewis1988/lean,dselsam/lean,leanprover-community/lean,dselsam/lean,leanprover/lean,fpvandoorn/lean,johoelzl/lean,fgdorais/lean,rlewis1988/lean,soonhokong/lean-windows,avigad/lean,digama0/lean,fpvandoorn/lean,leanprover-community/lean,digama0/lean,soonhokong/lean-osx,soonhokong/lean-windows,soonhokong/lean-osx,johoelzl/lean,johoelzl/lean,soonhokong/lean-windows,johoelzl/lean,johoelzl/lean,leanprover-community/lean,leodemoura/lean,Kha/lean,dselsam/lean,leodemoura/lean,soonhokong/lean-osx,rlewis1988/lean,fgdorais/lean,fgdorais/lean,leodemoura/lean,soonhokong/lean-windows,avigad/lean,digama0/lean,dselsam/lean,fpvandoorn/lean,johoelzl/lean,rlewis1988/lean,rlewis1988/lean,avigad/lean,fgdorais/lean,soonhokong/lean-osx,leodemoura/lean,avigad/lean,leanprover/lean,digama0/lean,soonhokong/lean-osx,fpvandoorn/lean,soonhokong/lean-windows,dselsam/lean,Kha/lean,dselsam/lean,leanprover/lean,leanprover-community/lean,digama0/lean,fpvandoorn/lean,Kha/lean,rlewis1988/lean,fgdorais/lean,Kha/lean,avigad/lean,leanprover/lean,leanprover/lean,leanprover-community/lean