chore: bump toolchain to v4.15.0

#281 adapt code to v4.15.0 and fix long heartbeats, e.g., toDualRep_apply_eq_contrOneTwoLeft.

---------

Co-authored-by: jstoobysmith <72603918+jstoobysmith@users.noreply.github.com>

HepLean/AnomalyCancellation/PureU1/Even/Parameterization.lean

@@ -116,7 +116,6 @@ theorem generic_case {S : (PureU1 (2 * n.succ)).Sols} (h : GenericCase S) :
   rw [parameterization]
   apply ACCSystem.Sols.ext
   rw [parameterizationAsLinear_val]
-  change S.val = _ • (_ • P g + _• P! f)
   rw [anomalyFree_param _ _ hS]
   rw [neg_neg, ← smul_add, smul_smul, inv_mul_cancel₀, one_smul]
   · exact hS

HepLean/AnomalyCancellation/PureU1/LineInPlaneCond.lean

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Joseph Tooby-Smith
 -/
 import HepLean.AnomalyCancellation.PureU1.ConstAbs
+import Mathlib.Tactic.FieldSimp
 /-!
 # Line in plane condition
 

HepLean/AnomalyCancellation/PureU1/Odd/BasisLinear.lean

@@ -515,7 +515,6 @@ lemma Pa_zero (f g : Fin n.succ → ℚ) (h : Pa f g = 0) :
   have h₃ := Pa_oddShiftShiftZero f g
   rw [h] at h₃
   change 0 = _ at h₃
-  simp only at h₃
   intro i
   have hinduc (iv : ℕ) (hiv : iv < n.succ) : f ⟨iv, hiv⟩ = 0 := by
     induction iv

HepLean/AnomalyCancellation/PureU1/Odd/Parameterization.lean

@@ -118,7 +118,6 @@ theorem generic_case {S : (PureU1 (2 * n.succ + 1)).Sols} (h : GenericCase S) :
   rw [parameterization]
   apply ACCSystem.Sols.ext
   rw [parameterizationAsLinear_val]
-  change S.val = _ • (_ • P g + _• P! f)
   rw [anomalyFree_param _ _ hS, neg_neg, ← smul_add, smul_smul, inv_mul_cancel₀, one_smul]
   · exact hS
   · simpa only [Nat.succ_eq_add_one, accCubeTriLinSymm_toFun_apply_apply, ne_eq,

HepLean/AnomalyCancellation/PureU1/Permutations.lean

@@ -5,6 +5,7 @@ Authors: Joseph Tooby-Smith
 -/
 import HepLean.AnomalyCancellation.PureU1.Basic
 import HepLean.AnomalyCancellation.GroupActions
+import Mathlib.Logic.Equiv.Fintype
 /-!
 # Permutations of Pure U(1) ACC