Drop allow-reresolve input from downgrade workflow(s) (#3728)

The reusable SciML/.github downgrade workflows now always use
allow_reresolve: false and no longer accept an allow-reresolve input
(see SciML/.github#71). Remove the now-invalid input so this caller keeps
working once @v1 is retagged.

Co-authored-by: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

.github/workflows/Downgrade.yml

@@ -25,5 +25,4 @@ jobs:
       julia-version: "1.11"
       group: "InterfaceI"
       skip: "Pkg,TOML,Statistics,LinearAlgebra,SparseArrays,InteractiveUtils"
-      allow-reresolve: true
     secrets: "inherit"

.github/workflows/DowngradeSublibraries.yml

@@ -24,5 +24,4 @@ jobs:
       skip: "Pkg,TOML,Statistics,LinearAlgebra,SparseArrays,InteractiveUtils,OrdinaryDiffEqCore,OrdinaryDiffEqNonlinearSolve,OrdinaryDiffEqDifferentiation"
       group-env-name: "ODEDIFFEQ_TEST_GROUP"
       group-env-value: "Core"
-      allow-reresolve: true
       # Every lib/* sublibrary is downgrade-tested (projects auto-discovered, no exclusions).