Remove useless try-with blocks in congruence.
Remove useless try-with blocks in congruence.

The inner body was not raising any exception since it was in the monad,
and even if it did so, the enter block would have caught it.

SkySkimmer/coq,Zimmi48/coq,coq/coq,ejgallego/coq,SkySkimmer/coq,SkySkimmer/coq,gares/coq,Zimmi48/coq,JasonGross/coq,gares/coq,ejgallego/coq,silene/coq,ejgallego/coq,SkySkimmer/coq,ejgallego/coq,coq/coq,Zimmi48/coq,gares/coq,JasonGross/coq,JasonGross/coq,JasonGross/coq,silene/coq,coq/coq,silene/coq,coq/coq,gares/coq,Zimmi48/coq,gares/coq