fix(frontends/lean/definition_cmds): check_valid_end_of_equations
fix(frontends/lean/definition_cmds): check_valid_end_of_equations

'with' token was missing.

leodemoura/lean,digama0/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,avigad/lean,digama0/lean,leodemoura/lean,johoelzl/lean,Kha/lean,Kha/lean,leanprover-community/lean,Kha/lean,Kha/lean,rlewis1988/lean,fpvandoorn/lean,dselsam/lean,avigad/lean,digama0/lean,johoelzl/lean,digama0/lean,digama0/lean,digama0/lean,avigad/lean,avigad/lean,johoelzl/lean,johoelzl/lean,rlewis1988/lean,avigad/lean,leanprover/lean,fpvandoorn/lean,leodemoura/lean,dselsam/lean,rlewis1988/lean,dselsam/lean,leanprover-community/lean,Kha/lean,johoelzl/lean,dselsam/lean,fpvandoorn/lean,leodemoura/lean,Kha/lean,leanprover/lean,leanprover/lean,dselsam/lean,johoelzl/lean,fpvandoorn/lean,fpvandoorn/lean,rlewis1988/lean,leodemoura/lean,leanprover/lean,leanprover/lean,leanprover-community/lean,rlewis1988/lean,fpvandoorn/lean,leanprover/lean,rlewis1988/lean,avigad/lean,leodemoura/lean,dselsam/lean