Case C-450/21: Order of the Court (Sixth Chamber) of 18 May 2022 (request for a preliminary ruling from the Tribunale ordinario di Vercelli — Italy) — UC v Ministero dell’Istruzione (Reference for a preliminary ruling — Article 99 of the Rules of Procedure of the Court of Justice — Social policy — Directive 1999/70/EC — Framework agreement on fixed-term work concluded by ETUC, UNICE and CEEP — Clause 4(1) — Principle of non-discrimination — Concept of ‘employment conditions’ — Allowance to support the in-service training of teachers and to enhance their professional skills)