benchs: fix 2020 benchmark formulae

In the latest version of RERS, the inputs is
slightly modified, our script failed the translation

* benchs/RERS/2020-Problem1-ltl.go.formulae.txt,
benchs/RERS/2020-Problem2-ltl.go.formulae.txt,
benchs/RERS/2020-Problem4-ltl.go.formulae.txt,
benchs/RERS/2020-Problem5-ltl.go.formulae.txt,
benchs/RERS/2020-Problem7-ltl.go.formulae.txt: Here.
1 job for er/bb in 2 minutes and 28 seconds
Status Job ID Name Coverage
  Test
passed #119245
debian-stable-gcc

00:02:28