Allow DomainSets 0.8

[ChrisRackauckas-Claude]

Please ignore until reviewed by @ChrisRackauckas.

What

Widen the DomainSets compat bound from 0.7 to 0.7, 0.8 and bump the version to 0.1.25.

Why

This unblocks the DomainSets 0.7 -> 0.8 dependabot bump in MethodOfLines.jl (SciML/MethodOfLines.jl#564). That PR currently fails to resolve because PDEBase (a MethodOfLines dependency) still pins DomainSets = "0.7":

ERROR: LoadError: Unsatisfiable requirements detected for package PDEBase [a7812802]:
 └─restricted by compatibility requirements with DomainSets [5b8099bc] to versions: uninstalled — no versions left
caused by: empty intersection between DomainSets@0.7.18 and project compatibility 0.8

DomainSets 0.8 breaking changes and why they don't affect PDEBase

DomainSets v0.8.0 (JuliaApproximation/DomainSets.jl#178):

1. Removed an old type piracy so DomainSets.× and LinearAlgebra.× are now distinct functions.
2. Unexported some internal symbols that now live in FunctionMaps.jl.

PDEBase's only DomainSets usage is in src/variable_map.jl:

x => (DomainSets.infimum(xdomain.domain), DomainSets.supremum(xdomain.domain))

Both infimum and supremum are fully qualified and remain exported in DomainSets 0.8 (verified locally), and PDEBase uses no bare × and no unexported internals. So no source changes are required — only the compat bound.

Local verification

DomainSets 0.8.0 was confirmed to provide every name PDEBase/MethodOfLines rely on:

DomainSets version: 0.8.0
infimum          defined=true exported=true
supremum         defined=true exported=true
Interval         defined=true exported=true
ClosedInterval   defined=true exported=true

A MethodOfLines test environment with this PDEBase branch + the matching ModelingToolkitBase compat bump developed in resolves DomainSets to 0.8.0 and runs the MethodOfLines Components and Diffusion test groups (see the MethodOfLines PR for full output). PDEBase precompiles cleanly against DomainSets 0.8.0.

Note: PDEBase's own Pkg.test (which pulls ModelingToolkit) cannot resolve DomainSets 0.8 until ModelingToolkitBase also admits it — see the companion ModelingToolkit PR. PDEBase itself is source-compatible; this is purely a transitive resolver constraint.

🤖 Generated with Claude Code

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Part of the DomainSets 0.8 set: SciML/MethodOfLines.jl#565 (consumer), SciML/ModelingToolkit.jl#4586 (ModelingToolkitBase, the other 0.7 pin).