Breaking changes from dependency update in PR #1004: MethodOfLines incompatible with Symbolics 7

[ChrisRackauckas-Claude]

Summary

PR #1004 updates Symbolics to 7.4.1, SymbolicUtils to 4.10.0, and ModelingToolkit to 11.4.0, but introduces a dependency conflict because MethodOfLines (a test dependency) does not yet support Symbolics 7.x.

Error

ERROR: LoadError: Unsatisfiable requirements detected for package MethodOfLines [94925ecb]:
 MethodOfLines [94925ecb] log:
 ├─possible versions are: 0.1.0 - 0.11.9 or uninstalled
 ├─restricted to versions 0.11.6 - 0.11 by project [1f79093d]
 └─restricted by compatibility requirements with Symbolics [0c5d862f] to versions: uninstalled — no versions left

Root Cause

• NeuralPDE uses MethodOfLines as a test dependency (in test/dgm_tests.jl for Burger's equation)
• MethodOfLines currently only supports Symbolics = "6" (not Symbolics 7.x)
• There are open PRs in MethodOfLines to add Symbolics 7 compat (CompatHelper: bump compat for Symbolics to 7, (keep existing compat) MethodOfLines.jl#486, test master #487), but they are failing CI, indicating code changes are needed

Suggested Next Steps

Option 1: Wait for MethodOfLines update (Recommended)

1. Wait for CompatHelper: bump compat for Symbolics to 7, (keep existing compat) MethodOfLines.jl#486 to be fixed and merged
2. Once MethodOfLines supports Symbolics 7, this PR can proceed

Option 2: Temporarily remove MethodOfLines dependency

1. Remove MethodOfLines from [extras] and test = [...] in Project.toml
2. Skip or comment out the Burger's equation test that uses MOLFiniteDifference
3. Re-add MethodOfLines once it supports Symbolics 7

Option 3: Pin to older Symbolics

1. Keep using Symbolics 6.x until MethodOfLines is updated
2. Close PR build(deps): bump the all-julia-packages group across 2 directories with 3 updates #1004 for now

Affected Files

• test/dgm_tests.jl: Uses MethodOfLines for the Burger's equation test (lines 100-153)
• docs/src/tutorials/dgm.md: Documentation using MethodOfLines

cc @ChrisRackauckas

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