Applique le renommage d'echelon_bourse issu d'openfisca-france v52.0.0

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Thu Jul 15 20:53:18 2021 +0100
#
# On branch msa_openfisca_france_local_AidesEureEtLoirs1
# Your branch is ahead of 'origin/msa_openfisca_france_local_AidesEureEtLoirs1' by 1 commit.
#   (use "git push" to publish your local commits)
#
# Changes to be committed:
#	modified:   openfisca_france_local/metropoles/rennes/mon_aide.py
#	modified:   openfisca_france_local/metropoles/strasbourg/tarification_solidaire_transports.py
#	modified:   openfisca_france_local/metropoles/toulouse/tisseo/jeunes.py
#	modified:   tests/metropoles/rennes/mon_aide.yaml
#	modified:   tests/metropoles/strasbourg/etudiant.yaml
#	modified:   tests/metropoles/toulouse/tisseo/jeunes.yaml
#
